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By T. Yalcin

It is well recognized that machine type and machine characteristics play vital roles in the successful application of froth flotation in mineral processing. Since the early 1900s, a multitude of machine designs have been and are still being introduced in an attempt to improve flotation efficiency. Machines based on mechanical agitation have been the most dominant in industrial practice. However, in recent years there has been a growing interest in pneumatic flotation units because of their claimed simplicity, low cost, high throughput and good metallurgical performance. This work was carried out to assess the effectiveness of pneumatic flotation on a magnetite ore. The method was applied using a prototype pneumatic flotation device that utilized a suitable nozzle for bubble generation. Important variables of the process were examined and optimized, including the nozzle size, air flow rate and froth thickness. Further tests were conducted to determine the influence of frother dosage and to explore the improvements that could be made on concentrate grade and recovery by cleaning and scavenging. Under the best test conditions, an iron concentrate was obtained with a grade of 66.4% Fe and a recovery of 97.7%. Particularly, the recovery was superior in comparison to that of mechanical flotation. This was attributed to the ability of pneumatic flotation to create and maintain a relatively thick froth layer.

Jan 1, 2002

By B. C. Haimson

The Committee on Rapid Excavation of the National Research Council has recognized in its 1968 report the need for "improvement of rock-mechanics techniques for measuring subsurface stress field in deep boreholes and for determining stress distribution in walls of underground excavations". The technique recommended in this paper as being most suitable for both deep hole and tunnel wall stress determination is Hydraulic Fracturing. Using this method stresses are calculated directly from the fluid pressures necessary to initiate and extend a fracture away from a borehole. Stress determination by hydraulic fracturing is rather insensitive to inhomogeneity or anisotropy, is not limited in depth except by the length of the hole, requires simple equipment which is commercially available, and can be carried out by unskilled personnel. The method has been worked out theoretically and extensively tested and verified in the laboratory. A number of field tests in deep holes ranging from 300 to 6300 ft have yielded surprisingly good results. Preliminary underground tests have been very encouraging and most recent measurements in a tunnel complex at the Nevada Test Site yielded stresses that were both consistent and reasonable when compared with the expected directionsand magnitudes. It is recommended that hydraulic fracturing be considered as a method of in-situ stress measurement both in the pre-excavation stage of design and during tunneling.

Jan 1, 1974

By E. G. Kelly

Many methods of evaluating the efficiency of mineral separations have been described in the literature. In most cases, these present the efficiency as a single number. This paper argues that single-number measures of efficiency are inadequate because they seldom allow reliable comparisons, and are unlikely to correspond to the optimum operating conditions. To realistically make comparisons, it is necessary to distinguish the particle-induced component from the equipment- induced component. In a number of situations where the separating property can be identified (such as in gravity concentration and classification), this can often be done. However, in more complicated systems, such as flotation, this has not been possible. A technique is described whereby particle and equipment contributions to efficiency can be distinguished without the need to define the separation property. Because smelter schedules define a boundary correlation between grade and recovery, they generate some of the better single¬-number measures of efficiency, but even these have limitations.

Jan 1, 1991

By David M. Mchaina, Michel Grenier, Stephen G. Hardcastle

An airborne dust survey was conducted at the Arthur W. White mine of Dickenson Mines Limited by CANMET/MRL and Dickenson Mines Limited Staff in April 1990 for the purpose of evaluating environmental conditions underground and in the surface mining plants. The survey was designed to measure respirable silica, total arsenic and lead concentrations at several workplaces. In addition, settled dust and rock samples were collected from workplaces and analysed for total arsenic content. More importantly, arsenic exposure data were needed to evaluate the impact of Ontario Regulation 176/86 as amended by Ontario Regulation 23/87. A total of 165 area and personal air filter samples were collected during the study. Of these, 85, 67 and 13 samples were for arsenic, silica and lead respectively. Sampling aid analyses were performed according to the Ontario Ministry of Labour Regulations. More than 90% of the workplaces sampled for respirable silica, total arsenic and lead were below the Ontario Ministry of Labour Regulations; and 10% of the workplaces sampled for arsenic shaved concentrations above the Threshold Limit value (TLV) proposed in the Ontario Regulation 176/86 as amended by Ontario Regulation 23/87. These results were used to identify occupations and/or workplaces where more sampling and control measures were required respirable silica, total arsenic and lead. This paper describes the results of the dust sampling program conducted at Dickenson Mines Limited.

Jan 1, 1991

By Gerald Zink

The object of underground excavation--apart from mining-- is to create an opening to serve as a part of some useful structure. The value of the opening lies in its conformity to the design configuration and its stability during the planned life of the structure. The wire saw could be used to excavate openings of high value at a cost competitive with present methods. First, a discussion of present methods will be used to explain where wire sawing fits in and how it should be applied. PRESENT EXCAVATION METHODS Tunnel Boring A recent advance in tunneling technology is the use of mechanical boring machines. There are many ways that a boring machine can reduce the cost of a tunnel or increase its value. I will mention a few of the advantages that have been demonstrated in tunneling projects. A tunnel can be bored without overbreak, allowing concrete lining to be poured to the design thickness without waste. Boring creates a minimum of disturbance to the tunnel wall, preserving the natural strength of the rock and reducing the amount of support which must be installed to maintain stability. A boring machine maintains the tunnel at its full dimensions and proper shape, and it leaves no rock projecting from the wall which must be trimmed off. The use of boring machines is presently limited to openings of uniform cross section and great length. If the previously mentioned attributes of mechanical boring could be applied to excavation of a wide variety of chambers and passages, then a corresponding decrease in cost and gain in value would be possible for chambers.

Jan 1, 1974

By Slavoljub D. Maksimovic, Steve J. Page

The Bureau of Mines measured respirable dust emission rates from overburden drilling at a surface coal mine and the transport of this dust to downwind locations. The emission rates were estimated by using multiple gravimetric dust samplers mounted on a cross-shaped tripod located immediately downwind of the drill. The transport of this dust was measured at more distant downwind locations by a combination of respirable gravimetric sampling and integrated bag sampling of sulfur hexafluoride (SF6), which was used as a tracer gas. Two modes of sampling were used: (1) At five sampling locations arranged in a semicircle around the drill. The radius of this arc ranged from 15.85 m (52 ft) to 71.32 m (234 ft). (2) In-line sampling at downwind locations with samplers located at intervals of either 10.67 m (35 ft) or 15.24 m (50 ft) for a total distance of 76.20 m (250 ft). Samples were taken 1 .22 m to 1.52 m (4 to 5 ft) above ground level. Test results for the semicircular test arrangements showed that at any downwind location, the maximum contribution of respirable dust due specifically to the drilling operation was 42%; the average for eight tests was 13.6%. In general, there was no correlation between the downwind distance of this maximum contribution and the maximum contribution itself because of changing wind direction. Test results for the in-line arrangements indicated that the transport of the dust from the drilling operation usually decreases rapidly with distance and that, even though the drill dust may produce significant health hazards for the drill operator and drill helper (or other personnel in the immediate vicinity), the exposure of downwind personnel to drill-generated dust may not be a significant problem.

Jan 1, 1987

By A. English, Edward Martinez, L. A. Haas, N. W. Johnson, Harrison Copper, M. E. Tawil, C. C. Harris, G. V. Jergensen, D. Halbe, M. P. Amsden

Declining US ore grades along with skyrocketing energy, materials, labor, and regulatory costs underscored the urgency for technological innovation in the mineral processing area. Re¬liance on the scale-up and automation of unit operations was the sector's primary battle plan. Debate continues on the upper size limit of concentrating plants and whether process controls should be centralized or distributed in the mill. In the materials handling area, the economics of large-scale and mobile systems, particularly conveyors, were well documented in the literature. Comminution, the most costly and energy consuming area of the processing flowsheet, saw improvements in process controls and liner designs. The trend toward larger grinding units stalled somewhat during the year owing to some operational problems at commercial plants. Research and development of apparently less expensive physical separation processes-that also boast recovery of cleaner and more environmentally acceptable products -gained momentum during the year. Because of escalating capital cost requirements for new plant capacity, the year saw a greater interest by mill designers to re-examine existing capacity. The focus here is clearly to modify or retrofit unit operations with more efficient components as an alternative to installing more costly new equipment. The problems facing the processing sector during the 1970s can be expected to continue in the decade ahead. Technological gains from scale-up and process controls appear

Jan 5, 1980

By Mark L. Mott

The Pittsburgh Safety and Health Technology Center of the Mine Safety and Health Administration (MSHA) has developed the Mine Emergency Responsiveness Development (MERD) program to improve the reaction and re¬sponse of mine personnel in mine emergency situations. The MERD program simulates problems that may occur in underground mine fires and explosions or surface mine accidents. Since its inception in 1982, the MERD program has been presented to MSHA, industry, labor and state government personnel. This versatile program is easily adapted to suit various training requirements. In 1992, a Mine Simulation Laboratory was built at the Natinal Mine Health and Safety Academy, Beckley, WV, to improve training for mine emergencies and prevention and fighting of mine fires. This facility is capability of simulating a coal mine and metal-non-metal mine for training purposes. It has been included in the MERD program to provide realistic and practical training for mine rescue teams and MERD partici¬pants in advanced mine emergency operations. The objectives of the MERD program are to improve the organizational and management skills of the participants in a rescue and recovery operation and provide a better understanding of the importance that various roles have on the overall organization and the importance of their interaction. The MERD program is not intended to provide the participants with all of the abilities and knowledge required to respond effectively to a mine emergency. Rather, it is intended to give the participant an opportunity to experience the emotions, frustrations and successes of a mine emergency without having to actually be involved in one. The participants are expected to return to their regular jobs with a greater appreciation of the environment in which emergency operations take place. Experience in mine emergencies is extremely limited in the industry today. The participants are encouraged to use the knowledge gained during a MERD program to develop or enhance a mine emergency plan suitable to their needs.

Jan 1, 1993

By D. A. Saint Don, M. Prueher, S. Barnwell

With the current changes in technology, multiple methods are now available for aggregate resource identification. From Sonic to Coring, Reverse Circulation to Percussive, there are many choices to make regarding drilling technology. The discussion will outline the methods above with focus on aggregate investigation and highlight the new technologies that will make a difference in your search.

Jan 1, 2004

By John R. Thalimer

For the past four years the U.S. Bureau of Mines has investigated the early detection of insulation failure in squirrel cage induction motors. Data modeling techniques based on values calculated from a motor's voltage and current phasors were used to produce a pair of polynomial equations that calculate a motor's insulation leakage current and power. This paper describes a prototype system using these models that monitors six motors on a continuous miner for insulation leakage in order to anticipate insulation failure. The system consists of a motor-data system for each motor on the machine, a control computer located some ' distance from the miner, and a serial bus to interconnect these items. Each motor-data system consists of an analog interface to the motor's voltages and currents, a single-board computer that reads digitized data and calculates voltage and current phasors, and a bus node that interfaces the single-board computer with the serial bus. The control computer can request and receive phasor data from any motor-data system on the bus. Using models developed at the Bureau, the control computer calculates and displays two deterioration values for each motor, one for leakage current and the other for leakage power. These values are then stored into a database from which the user can display them over time.

Jan 1, 1992

A group of geologists is located in a remote area of North America, without telephone lines, electricity or even running water. They have spent days accumulating data for a mining company that is eager to receive any information about the dig. But the team does not have access to a wired communications infrastructure. So the geologists must wait until they get to the nearest town to transmit their data. TMI Communications has a mobile satellite communication system that allows geologists in the field to transmit their data from remote locations. The company's satellite is the heart of its North American mobile communications network. This satellite turns all of North America, including Canada, Mexico and the Caribbean into a single digital communications cell. Traditional terrestrial communications systems, such as dedicated phone lines or cellular systems, cannot handle a remote geological exploration camp's extensive communications needs. Cellular technology, where available, has high costs and limited applications. For geologists in the isolated areas of North America, accessible and reliable phone service is vital to success. For those who have established temporary camps, TMI Communications' satellite phone service has improved the speed and accuracy of their communications with home base. This wireless network is suited to meet the needs of existing data applications and the challenges of new ones. It can support any one- or two-way, fixed or mobile data transfer. TMI's network enables geologists to transmit exploration results, spreadsheet information and location co- ordinates to anywhere in the world, at any time. This is important if a team needs to relay vital data back to its headquarters to support immediate decision making on a prospect site or a find.

Jan 1, 1999

By A. G. Mayton, L. Adler

The paper under discussion provides an excellent and concise study of compartment ergonomics for thin seam equipment. However, in accomplishing this, some very important operational aspects were ignored. Since these are likely to be determinant, the authors' response is solicited. The novel shuttle car with its cross-car, end-mounted compartment is operationally very different from the current one. The latter can be considered a highly mobile extension of the continuous miner or loader, with a pass-through conveyor, dump boom, and extra storage. As such, the vehicle's kinematics are the simple "I," or shuttle pattern, bent for going around pillars, with an intermediate stop at the "change-out point" (Adler, 1986 ). The action of the cable reel adjusts well to this pattern. The proposed shuttle car's motion either superimposes a "Y," time is lost (5 seconds) for each cycle, space is needed, line of sight is compromised, and a cable anchor is probably required at the dump. A chute is almost prohibitive in construction time and cost. The lack of a dump boom further curtails flexibility in the proposal. The value of a standard hand and opposite standard hand configuration also needs consideration. Many front-end loaders have a rocker (overshot) capability that is designed to achieve an "I” pattern. And crawler loaders sometimes use a side dumping bucket variant for the same purpose. These examples indicate the pattern's importance. For underground, thin seam application, the ram car has become popular. This is an articulated truck, battery-powered, and with an ejector dump. Its operational patterns would be similar to the novel shuttle car, except without the loading flexibility provided by a conveyor. Since the cab location of the proposed shuttle car largely obviates some of the major advantages of the present shuttle car, the question arises whether this configuration could be adapted to the current ram car and scoop

Jan 1, 1991

By T. Cohen

Technological innovation in the minerals industry must be driven by the need to improve performance according to social, as well as environmental, safety, efficiency and production criteria. This paper outlines the possibilities and rationale for incorporating constructive technology assessment into technology research and development within the CSIRO Minerals Down Under National Research Flagship (MDU). The paper develops a process of Social License in Design that attempts to address the future social challenges and opportunities of a technology during development by utilising forecasting techniques and accounting for the perspectives and values of decision makers and likely stakeholders. Interviews with senior technologists and social scientists within MDU reveal the institutional context into which the Social License in Design process is to be situated and highlight key factors that may inhibit or enhance its uptake.

Jan 1, 2011

By Robert D. Talvensaari

It is indeed an honor for White Pine, as a member of the copper mining industry, to participate in this Rapid Excavation Conference. Although our presentation, as the title indicates, is not a success story, we foresee, through our experience, future application of boring machines and rapid excavation equipment in the hard rock mining industry. One might ask what a copper mining company would be doing with boring machines and why the gamble on a high-cost, capital investment for a relatively untried application. Perhaps a little background on the White Pine mine and its geology will explain our daring and speculative motives. THE WHITE PINE MINE The White Pine Copper Company, a wholly-owned subsidiary of Copper Range Company, operates a mine, mill and smelter at White Pine, Michigan in the western Upper Peninsula approximately 6 miles due south of Lake Superior. We employ approximately 3,000 people from the surrounding area and mine approximately 25,500 tons of low grade (1%) copper ore per day. The orebody is contained within several distinct sedimentary horizons that comprise the lower 20 feet of a Precambrian formation known as the Nonesuch Shale. Numerous articles and reports have described many aspects of the White Pine operation and the geology. I will brief you only on that criteria which precipitated our interest in rapid excavation equipment and techniques, specifically, boring machines. Mineralogical and optical studies have demonstrated that the siltstones, sandstone and shale beds all contain relatively barren and discrete particles of quartz (25%), feldspar and mica, bonded with

Jan 1, 1974

By E. F. C. Ferrett

The benefits derived from the use of main fan evasees or diffusers are well known. If a well designed evasee is fitted to a fan either more air will flow through it or the same air flow rate will be discharged at a lower fan speed. This latter possibility will reduce the air power requirement of the mine, the fan input power and the overall energy costs. Despite these apparent advantages, many reports have been received from the industry of poor evasee performance. After examination, it appears that these problems are often caused by installation difficulties or inaccurate design procedures. The performance of an evasee is affected by several independent factors. Some of these factors describe the evasee geometry whilst others are concerned with the behaviour of the air as it passes through the evasee. This paper shows that the divergence angle is by no means the only ;important parameter which affects evasee performance and that the size of the inlet boundary layer has a significant influence. The performance of evasees of differing geometric shape are compared and the criterion to be used for optimum performance is discussed. It is shown that the commonly used evasee efficiency is a poor indicator of good performance. Recent work by the author and others is evaluated and a simple design. guide discussed. For more sophisticated work, details of a. computer program are provided. Finally, a brief resume of the performance of truncated diffusers is given. Since compressibility effects can be ignored for most mining applications, incompressible flow has been assumed for most of this paper.

Jan 1, 1980

By D. Constantinides

In 1981 a Zn-Ag-Pb deposit was discovered in the vicinity of Molai, Greece. Subsequently, it was determined to be of the Kuroko type. The geology of various areas in the southeast Peloponnesean Peninsula is similar to that of the Molai deposit. Since favorable geologic criteria are present, absent, or unknown in varying degrees in all areas, it was deemed necessary to classify and rank the prospective areas according to the level of information available. For each level of information, an ore discovery model based on pragmatic exploration criteria was developed, enabling the favorability of occurrence to be calculated for each area. A Monte Carlo simulation was used to calculate the probabilities, the input data consisting of quantitative and qualitative estimates of the geologic criteria for each area. Three levels of information were modeled : Level A consisted of 9 criteria, level B of 12 criteria, and level C of 20 criteria. The three levels of information were tested on the Molai area. The results exceeded expectations, showing the gen¬eral trends which control mineralization at the lowest level of information. With an increase in the level of information, geological trends become more evident and a differentiation can be made between areas containing Cu mineralization, exhibiting a low probability, and areas likely to contain Zn-Ag-Pb mineralization. The models were then applied to the neighboring areas - only level A and B were available.

Jan 1, 1986

By Walter E. Cook

BOB FALCONER: Without further ado I'm going to introduce our first speaker, Walt Cook. Walt is president of Strata Resources and is here with his business partner Joe Nenni. Joe would you stand up here. You'll be on the tag-team with Walt. Walt and Joe are in a consulting business associated with coal as well as metal and nonmetal industries. Their presentation will be on gainsharing. WALTER COOK: How many of you have gainsharing plans in place currently at your location? [show of hands] A considerable number-more than about half the room. Of those plans, how many of them do you consider as meeting your needs and being successful? [show of hands, far fewer, general audience laughter] You have all at least heard the word "gainsharing." Some of you undoubtedly aren't quite sure what gainsharing is, while others obviously have gainsharing plans in place and are looking for ways to improve them. In the short time I have now I'll be able to give you a precursory look at gainsharing and some brief ideas on where to look to improve your current plans. Over the years, I've found that it is often best to explain gainsharing by comparing it to other forms of employee compensation

Jan 1, 1998

By F. Grandjacques

INTRODUCTION Selective Reduction of Nickel in Oxidized Ores Oxidized nickel ores, either garnieritic or lateritic, contain much more iron than nickel. The regular carbon reduction in an electric furnace is operated in such a manner that the greater part of iron oxides is reduced simultaneously with nickel oxide, resulting in a low nickel content ferronickel. In order that the nickel content of residual slag may be suitably low, -excess carbon must be fed so that the carbon content of the ferronickel thus obtained is that of casting iron. The metal also contains other impurities such as silicon, chrome, etc. In order to convert the casting iron into slightly carburized ferronickel with high nickel content, the greater part of the carbon and more than half the iron contained therein must be oxidized by means of oxygen. Energy is thus consumed as carbon, and power to reduce iron oxides, and more energy is consumed as oxygen to re-oxidize the iron contained. This method can be economically adopted for nickel ores with grades ranging around 2. 5 to 370, but it gets excessively costly when nickel grade falls below these values. This is why, for nickel ores with low nickel grades and high iron content, studies were conducted to develop a selective reduction process which, while reducing only a small part of the iron oxide, would provide efficient reduction of nickel oxide. Rich ferronickel is thereby obtained, with nickel content ranging around 30 to 50%. Due to the presence of slag with a high iron oxide content, the metal thus

Jan 1, 1979

By Carl R. Peterson, John Herrick

INTRODUCTION The need for substantial advances in underground excavation technology has produced considerable research activity on a wide variety of concepts under a variety of Government funded programs. One goal of this "Rapid Excavation" effort has been the development of a means to apply the well-known virtues, both technical and economic, of the drill and blast method in a continuous process. The spiral blast concept, aimed at this specific goal, has been funded for initial studies (1) by the ARPA Rapid Excavation Program and, for the experimental work reported herein, by the Department of Transportation (2). The economy enjoyed by the drill and blast method stems from two factors: explosive energy is relatively cheap; and this energy is released so as to cause rock fragmentation largely through tensile failures. The relative ease and efficiency of tensile rock failures have long been recognized. The drill and blast process of course cannot be truly continuous since drilling and blasting (and other necessary functions) simply are separate, distinct operations. Although some surface explosive work has been done to avoid the need for drilled blast holes (3) it does appear that the high performance associated with explosive excavation requires placement of the explosive beneath the rock surface. This paper describes studies of blasting pattern which, in simplest terms, replaces the occasional heavy blast of conventional practice with frequent, much smaller blasts. The objective, of course, is to reduce the size of individual blasts

Jan 1, 1974

By Richard Stoltz, Gary Smith

This paper presents the findings of a face ventilation investigation, conducted by the Ventilation Division, Pittsburgh Health Technology Center, at a underground coal mine operating in the Illinois No. 5 coal seam. The purpose of the investigation was to evaluate the effectiveness of a blowing face ventilation system in controlling methane liberation in the face area while mining with brattice distances up to a maximum of 40 feet from the face (extended cut). The continuous miner on this section was remotely controlled and equipped with a machine mounted dust collector. Data collected during this investigation included methane concentrations, intake and return air quantities in the face area, and scrubber air quantities. In addition, a time study was conducted to correlate the methane peaks to activities in the face area. In conjunction with the face study on Section A, separate methane liberation studies were conducted on three additional sections: B, C, and D. This was done in order to compare intake methane concentrations and methane liberations from other sections in the mine to the test section. Calculations indicated that the minimum intake air quantity necessary at the inby end of the line brattice for the section investigated was 7,000 cfm. Due to the higher intake methane concentrations and average methane face liberations measured on three other sections, the minimum air quantities necessary at the inby end of the line brattice were determined to be 13,900 cfm, 11,100 cfm, and 15,000 cfm, respectively.

Jan 1, 1991