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By K. A. Sauer

Blasting can create severe interference for a mine's carbon monoxide based fire detection system. At the present time, without being able to differentiate between blast and non-blast carbon monoxide, a fire detection system must either set fairly high alarm levels for its sensors, or allow frequent "false" alarms to sound during blasting. This paper will introduce current work being done which will attempt to define characteristics of the carbon monoxide concentrations time curve for blasting. The work uses drift blasting for its data base as it is one of the more common forms of blasting. Future work with the data may produce a mathematical model which can be used to monitor and identify the carbon monoxide time curve for drift blasting.

Jan 1, 1989

By David E. Peterson, F. Merz

The Waihi Gold Mining Company Limited, Martha Hill Project was the first major hard rock mining operation following the resurgence of the mining industry in New Zealand. Because of its location adjoining a town and at the southern part of the sensitive Coromandel Peninsula, the operation received a high level of public scrutiny. Very srrict limits for effluent criteria had to be met and led to the necessity for advanced wastewater rreatment technology. The process technology selected was the copper catalysed oxidation of cyanide using hydrogen peroxide, with subsequent removal of heavy metals by precipitation and filrration. This paper discusses the adoption of environment limits together with the detailed description of the plant and design criteria. Data of the one year's operational history is also presented.

Jan 1, 1991

By H. N. McLeod, M. J. Thom

The use of cyanide in gold mining requires the careful handling and storage of cyanide rich tailings. Cyanide in groundwater can frequently be both persistent and mobile, so that tailings basins need to be designed to limit and collect seepage. Assessment of the potential environmental impact requires an understanding of the hydrogeologic regime, both before, during and after mining. Groundwater monitoring wells provide a basis for monitoring tailings pond behaviour and for assessing the impact of mitigative measures to reduce or control seepage. A case example of Cheni Gold Mines Lawyers Project in Canada is presented to illustrate the use of groundwater monitoring to determine the amount of cyanide degradation and attenuation between the tailings pond and the receiving environment.

Jan 1, 1991

By Harrie van Dijk

Feeding laterite nickel slurry into high pressure acid­leach (HPAL) autoclaves in an aggressive environment with slurries heated up to 200°C requires a special pump design. For decades the GEHO piston diaphragm pumps have been used for autoclave feeding at gold ore pressure oxidation plants with slurries up to l 77°C. Lessons learned from these installations have been instrumental in designing second generation feed pumps for processing laterite nickel with operating temperatures of 200°C and a flow rate of 400 m3/h. The Australian nickel industry is using momentarily 8 GEHO positive displacement piston diaphragm pumps. For this application six GEHO ZPM 900 "dropleg" pumps have been supplied to the Murrin Murrin project and two to Bulong.

Jan 1, 2000

By Rob Henson, Te-Lin Yau, Darryl Amick

The process industry faces tightening environmental regulations. In order to comply with these mandates, environmentally safe chemicals, such as oxygen and hydrogen perox­ide are becoming attractive oxidants. These oxidants appear benign but must be respected when involved in harsh environments. It is therefore important to address both the safety and suitability of materials selected for these environments. Otherwise, severe prob­lems, such as equipment failure or fire and explosion can occur. Laboratory and field experience will be used to discuss the perfor­mance of titanium, zirconium and Ti-45Nb alloy in piping systems for handling these environ­ments. Sealing methods for piping, pumps and valves of these metals will also be reviewed. For comparison, information on the performance of stainless alloys will be given.

Jan 1, 1993

By C. A. Fleming, C. J. Ferron, P. T. O'Kane, D. B. Dreisinger

The platinum group metals (PGM's) are typically recovered by flotation, smelting of the flotation concentrate to matte, and matte leaching. Concentrates too low grade to be processed economically by the conventional process require a new treatment route. PLATSOL, a new pressure leach process, was developed for the Northmet deposit and dissolves in one step base and precious metals (PGM's and gold). Various options exist to recover all pay metals from the leach liquor. The preferred option to date involves a solid-liquid separation, followed by sulphide precipitation of gold and the PGM's, and copper solvent extraction using commercial solvent extractants. This paper briefly summarises the process and the effect of the main leach parameters. Application of the PLATSOL process to various feedstocks is also presented.

Jan 1, 2000

By Michael J. Virnig, Kathryn C. Sole, Murdoch W. MacKenzie, Michael R. Davis

A solvent-extraction process has been developed for the removal of copper cyanide complexes from aqueous copper/gold cyanide solutions formed in gold-recovery circuits that treat ores containing cyanide-soluble copper. The process uses LIX® 7820, one of the LIX® 7800 reagent series developed by Henkel. It is based on a mixture of Aliquat® 336, a quaternary amine, modified with an alkylphenol, 4--nonylphenol. Extraction and stripping data for the base metal cyanides and thiocyanate are presented. Methods for the recove1y of copper and cyanide from the upgraded strip liquor are reviewed. A flowsheet based on this chemistry and a preliminary economic evaluation of a solvent-extraction circuit combined with the cyanide-recovery process developed by Metallgesellschaft Natural Resources (MNR) are also presented.

Jan 1, 1999

By L. Lichty

Treatment of refractory gold ores containing arsenic has always presented a major problem in their processing to recover the contained precious metal values. The major difficulties are concerned with lower recoveries and production of hazardous fumes, effluents and residues. Due to these arsenic related problems, many otherwise economically attractive precious metal deposits and dumps all over the world are not exploited. In recent years, treatment processes for refractory gold ores and concentrates have been explored. A few commercial operations employing roasting or pressure leaching have resulted. Roasting has limitations due to environmental constraints related to off gases. Pressure leaching involving high temperatures (180° to 200° C or 356° to 392° F) and pressures (2.75 MPa or 400 psi) is accompanied by high capital and operating costs.

Jan 1, 1990

By David R. Crouthamel, Francis L. Fong, Troy L. Page

This paper focuses on the results and the performance of the grouting program as a means to control groundwater infiltration during the excavation of the 7.7 km (25,160 lf.), 3.5m (11 ft. - 7 in.) diameter Inter-Island Tunnel beneath Boston Harbor in Massachusetts. Two major operations of grouting were performed - water cutoff grouting behind the tunnel heading after excavation and face grouting ahead of the Tunnel Boring Machine (TBM) operation. An array of products from cementitious to chemical grouts and various grouting procedures and equipment were employed to evaluate their effectiveness in controlling the water in-flows. Evaluation of the overall performance of each of the grouting rations, overall costs and comparison of face grouting versus post excavation grouting is made.

Jan 1, 1997

By Jack G. Pippenger

The Coteau Properties Co.'s Freedom mine is a surface operation near Beulah, ND that produces more than 13.6 Mt/a (15 million stpy) of lignite. Coteau, a subsidiary of North American Coal Corp., ranks among the largest mines in North America. In 1994, Coteau ranked eighth in annual coal sales, becoming the largest mine outside the Powder River Basin of northeastern Wyoming. However, for the Freedom mine to stand alongside the Powder River Basin heavyweights, Coteau had to overcome several obstacles. These included a coal seam with three-quarters the heating value and overburden-to-coal ratios three times higher than Powder River Basin mines. Coteau's ability to compete has been built around a program of continuous improvements in productivity, cost efficiency and innovation.

Jan 1, 1995

By P. N. H. Bhakta, X. P. V. Lei

The U.S. Bureau of Mines developed an alkaline oxidative pretreatment to increase the recovery of gold from refractory sulfide ores containing arsenopyrite (FeAsS) and/or pyrite (FeS2). Pretreatment of a low grade ore containing 0.4% FeAsS, 3.5% FeS2, and 2.74g/mt Au with 1.2m NaOH, 40 psig o2, 100° C, and 4 hr in a 2-L autoclave resulted in 94 to 96% sulfide oxidation. cyanidation of the pretreated residue resulted in 88% Au extraction compared to <20% Au extraction for untreated ore. Cyanide consumption was 0.25 kg NaCN per metric ton of ore. A flowsheet for treating sulfidic low-grade gold ore is proposed.

Jan 1, 1990

By John Turner, David Carey

The Robbins Mobile Miner demonstrates the successful combination of hard rock excavation technology and the latest electronic control technology. The mobile miner, a partial face hard rock tunneling machine, features a fully integrated control system relying on a Programmable Logic Controller (PLC). This PLC controls all functions: tramming, steering, boom swing, cutting depth, conveyor operation, air scrubbers, hopper loading and unloading, etc. The machine is fully instrumented allowing the PLC to monitor the results of all commands on a continuous basis, to record data, to evaluate developing problems, or to shut the machine down if necessary. The paper describes the development of the Robbins - Pasminco automated mobile miner and early testing at Pasminco Mining&apos;s Broken Hill Southern Operations, New South Wales, Australia.

Jan 1, 1993

By Fu Lizhu, Qiu Tingsheng

An application of water-system magnetizing technology for the mineral processing and hydrometallurgy is introduced in this paper. The water-system magnetizing technique flotation and cyanidation leaching test of vein-ore of gold-bearing and conventional technique flotation and cyanidation leaching of gold-bearing vein-ore was carried out. The best condition of water-system magnetizing was determined by orthogonal test. The results have shown that the water-system magnetizing technology may increase the efficiency of flotation and cyanidation leaching for gold. The industry-scale test results also show that it can increase flotation recovery by 1-3% and leaching extraction by 3-5% of a gold-bearing vein- ore. The interaction of magnetizing water-system with minerals was carried out and initially investigated.

Jan 1, 1995

By T. C. Eisele

Previous work by the authors has shown that the performance of a flotation column can be improved by the use of horizontal baffles. These baffles prevent axial mixing and also reduce "churning" of the froth by breaking up or preventing the formation of large air bubbles. In this paper, results from tracer experiments are presented that show the effects of horizontal baffles on the reproducibility and stability of the column operation. The baffles prevent random disturbances, such as unusually large air bubbles and turbulence, from rapidly propagating along the height of the column. Because these factors are responsible for much of the variations in column performance between tests, the result is that the horizontal baffles make the column performance more reproducible, with fewer short-term variations.

Jan 1, 1999

By A. Zutshi

Production of CO2 is an inevitable consequence of burning fossil fuels, with the only CO2 sequestration technique feasible in the immediate future being its injection in various geologic media. This paper discusses the factors that influence the injection, movement, and storage of CO2 into deep coal seams, while simultaneously increasing the production of methane. The results of a laboratory-scale study to evaluate the movement of CO2 in coal, its ability to displace methane, and the capacity of coal to retain CO2 are presented. The findings are compared with observations at one of the two field-scale pilot operations practicing CO2 injection in coal. Finally, the paper summarizes the research issues that require further investigation.

Jan 1, 2006

By John T. MacWaters, George H. Milly

INTRODUCTION This paper describes operational procedures and instrumentation which were developed to implement a patented method of detecting and locating uranium ore bodies. All equipment was designed for accurate and reliable use under difficult field conditions. Data resulting from these developments, some of which are incorporated in a companion paper for this conference*, have contributed to our understanding, of the nature and significance of naturally-occurring radon exposures. Further applications of these techniques may prove useful in studying anthropogenic radon in evaluating the significance of variability in radon flux, or in taking proper account of the contribution of natural radon to ambient radon concentrations, particularly in mineralized regions. OPERATIONAL PROCEDURES The uranium search technique employed by GEOMET begins with a [reconnaissance mode], which utilizes a series of ambient air filter samples taken from a moving or standing vehicle to detect anamalous concentrations of radon. These samples are normally taken at night under stable (temperature inversion) or neutral atmospheric conditions, to avoid the rapid dispersion of the radon clouds typical of daytime turbulent conditions. Radon daughters formed by the decay of radon quickly attach to ambient aerosol particles and are captured on the surface of a membrane filter during a five-minute sampling period. The filter is placed in a portable alpha scintillation counter, and a five-minute count is started at a preset time after the completion of the sampling period. This count is followed immediately by a second five-minute count to enable determination of the cloud age, based on consideration of the relative half-lives of the initial radon daughters. With the use of tables computed from the mathematics of the uranium decay process, and with the measured radon background accounted for, the first and second counts are used to estimate the time which has elapsed since the pure radon initially emanated from the earth&apos;s surface. This cloud age, combined with wind speed and direction measurements made at the beginning and end of each sample, as well as with an understanding of the effects of local terrain features on wind trajectory, provides an estimate of the Probable location of the source. In practice the reconnaissance mode involves one vehicle with a single operator to take the five-minute samples, moving or standing, along any available roads or trails in the area to be covered. Under the usual nighttime stable conditions the cool air flows downslope and downvalley, and the operator will pay special attention to locations along the axes and confluences of the natural downflow patterns. These facilitate sampling of large air drainage areas. Successful detection of sources of radon based on high concentrations of radon daughters, and substantiated by evidence of "fresh" clouds, are frequently made on the basis of a relatively few samples taken judiciously by an experienced operator during a reconnaissance. At this point he has a choice: he can continue to cover the designated reconnaissance area, leaving the localization of any anomalous radon detections to await the ranking of detections by priority, or he can continue with localization of the detected source, either alone or by radioing for another vehicle to assist in triangulation operations. Localization of a source involves skillful and experienced use of the continuously collected data on concentration, age, and wind speed and direction, together with knowledge of the terrain from observation and contour maps, and exploitation of the available roads. Since age ratios are dependent solely on proximity of the source and wind speed, decreasing [cloud ages] based on statistically significant increasing age ratios represent the most useful. information in localization. The [magnitude of the concentration] of radon daughter products is also useful; however, it may vary widely for a variety of reasons during sampling for a localization, thus making this a secondary parameter for localization. Large values of concentration are of course useful; typical results for successful detection of a strong anomaly would yield alpha counts ranging from 10 to 25 times background values. These counts are convertible to ambient radon concentrations by appropriate consideration of the decay process. Successful localizations of radon sources using this procedure with ambient atmospheric measurements normally will narrow a source location to within an area ranging in size from less than a quarter of a square mile to at most a square mile, and frequently give information on the probable shape of the source (in plan view) on the earth&apos;s surface. Judicious use of this procedure could undoubtedly provide finer localization, but the coarser results just described are adequate for this Phase of GEOMET&apos;s uranium exploration procedures.

Jan 1, 1981

By Tom Plouf, Deepak Malhotra

INTRODUCTION The U. S. mining industry experienced a severe recession in the early 1980&apos;s. This resulted in the realization that the domestic mining industry had to compete on a global basis and only the strong or the low-cost producers would survive. The economic viability of a mining company not only depended on maximizing mineral recovery but also on its ability to do so at minimum cost. Companies had to become more productive not only by cutting costs, but also by developing and/or evaluating new technologies in existing or new plants. Several innovative concepts, including in-pit crushing and conveying, fine crushing, improved classification equipment, flotation, column flotation, pressure filtration, etc., have been developed in recent years. This paper addresses the impact of new flotation concepts and equipment on mill design. MILL DESIGN PHILOSOPHY Modern mill design, especially for large capacity plants, has its foundation in minimizing capital and operating costs. Capital costs can be minimized by minimizing the various components of the capital cost: infrastructure, equipment, instrumentation, structural, initial spare parts costs, etc. All these costs are minimized by simplifying the mill design and/or process flowsheet. The simplified process flowsheet, where applicable, consists of a single stage primary crusher followed by a semiautogeneous - ball mill grinding circuit to produce feed for a flotation circuit. Multiple flotation circuits have been eliminated in most cases. These concepts minimize the cost and encourage the use of large capacity equipment while maintaining optimum metallurgical recovery. The philosophy of mill modernization/modification is generally driven by the desire to increase the mill capacity within the limits of the existing mill building. This need is facilitated by using large size flotation equipment and eliminating multiple parallel flotation circuits in order to minimize capital and operating costs. Conventional flotation machine development has paralleled this mill design philosophy. FLOTATION CELL DESIGN Since froth flotation has been the most widely used separation process for over half a century, one would expect that it would be possible to design and select flotation machines for specific applications based on scientific principles. But this has not been the case. Best judgment, experience and personal prejudice have played a key role in equipment selection. These factors, along with the difficulty of evaluating new concepts in commercial plants, has slowed progress in implementation and commercialization of innovative ideas and/or equipment. Conventional Flotation There have been no major technological advances in conventional flotation cell design in recent years. A recent flotation cell survey indicates that &apos;larger flotation cells are still the order of the day.”(1) A comprehensive review of design of flotation machines indicate that they have been mechanically redesigned and are generally simpler and easier to maintain and less expensive to manufacture. (2,3) The approximate chronological development of conventional cells from the 25 cubic foot cells to the 3000 cubic foot cells, which were recently installed at the Copperton concentrator of Utah Copper, is given in Table 1. Larger flotation cells are the obvious choice for new plants or plants looking for expansion because of the following reasons: • They have lower capital cost per unit volume • Installation costs are generally lower because fewer units require less space • Maintenance costs are lower because of fewer mechanisms • Power requirements (HP/ton dry feed) are generally lower • with increased flotation cell size as illustrated in Table 2 [Table 1. Conventional Flotation Cell Size Development Year Individual Cubic Cell Size, Feet 1925 25 1935 50 1960 100 1965 300 1970 500 1975 1,000 1980 1,500 1985 3,000]

Jan 1, 1989

By D. C. Torre

Since the early 1960s, there have been efforts to develop and produce reliable continuous haulage systems capable of taking the full output of a continuous miner and transporting it, in one continuous flow, from the face to the tipple. The majority of the successful continuous haulage systems were placed in operation in the early 1970s. These were all of the bridge conveyor type. They usually consisted of bridges and mobile bridge carriers (MBC) attached at the inby end to the continuous miner and at the outby end to the panel conveyor itself. These successful bridge conveyor continuous haulage systems are either of the belted or chain type. The most successful belt type continuous haulage systems are those manufactured and marketed by the Long-Airdox Co. Until early 1977, Jeffrey Mining Machinery Division manufactured and marketed the most successful chain conveyor type haulage sys¬tems. In 1977, Long-Airdox reentered the market with a chain-type system to complement its belted system. The original bridge-type continuous haulage system was introduced to the coal mining industry in the early 1960s by the old Long Co., a predecessor to the current Long-Airdox Co. These original units were of the chain conveyor type. In the early 1970s, there were also developments in continuous haulage, employing different material handling media. These in¬cluded the Serpentix, a flexible type belt, introduced by the Joy Manufacturing Co. There was also a serious attempt to introduce hydraulic-type continuous haulage by Consolidation Coal Co. and Conoco Research. Despite some startling successes, particularly with the bridge-type haulage systems, the general and widespread application of continuous haulage has eluded the mining industry. Some of the problems are related to underground conditions; others to people, both management and labor. One of the greatest obstacles to universal success continues to be the difficulty of accepting the philosophy as well as the machinery of continuous haulage. Nevertheless, efforts continue to spread the success of commercial and viable systems in the industry. There is also effort to improve on these systems, and on methods for their successful use. In addition, efforts continue, with private and public support, to develop new types of continuous haulage equipment and systems. Bridge Type System Developments Because they have already been successful in some US and overseas mines, new developments in bridge-type systems will first be touched on. The Long-Airdox Co. has continued to improve both its belted and chain continuous haulage system. In the belted system, the company recently introduced a new design that will be mainly applicable in higher coals and in noncoal mining applications, as shown in the accompanying figure. This new system is equipped with 305-mm-diam (12-in.-diam) pulleys in the bridges and mobile bridge carriers, in place of the 150-mm-diam (6 in.-diam) pulleys in the standard system. The modification is designed primarily to improve belt life and keep belt problems to a minimum. An operator, the Clinchfield Coal Co., a Division of Pittston Coal, developed the detaching of the bridge-type continuous haulage system from the miner by placing a mobile bridge carrier at the head of the string. However, Long-Airdox and Jeffrey have now made this an option to their at¬tached-type system. In the US, there are many chain type haulage systems detached from the miner with an extra MBC at the head. There are two such belted systems

Jan 7, 1982

By T. M. Gurr

It is estimated that in excess of one-half million chemicals are used throughout the American workplace. Hundreds of new chemicals are also being introduced into the workplace annually. Exposure to some of these chemicals can be harmful to workers and to the environment. The Occupational Safety and Health Administration (OSHA) estimates that approximately 25% of the U. S. labor force or approximately 25 million workers are exposed to one or more chemical hazards each year. OSHA has determined that this poses a serious problem for workers exposed to such chemicals. Chemical exposure may cause safety and health problems. Health problems can include a cause or contribution to heart ailments, kidney and lung damage, sterility, cancer, burns, and rashes. Safety hazards can include the potential to cause fires and explosions and other serious accidents.

Jan 1, 1989

By Norbert Steiner, Roy Norcross

For the desulfurization of weak SO2 gas streams, Degussa developed a process using dilute H2SO4 solution containing H2O2 instead of conventional gas scrubbing with all solid absorbent medium (limestone, MgO). The process is based on fast reaction of H2O2 with SO2 yielding H2SO4 up to 70% strength, depending on off-gas tem­perature. Compared to the conventional systems with typically < 95% efficiency, independent on the raw gas SO2 concentra­tion, residual SO2 concentrations of less than 20 mg!Nm3 can be easily achieved, corresponding to nearly 100% removal. These features render the H2O2 process a very attractive, low capital cost technology to retrofit existing conventional desulfurization plants.

Jan 1, 1996