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By George Munro

Heavy water inflows of up to 1350 1/sec in the 19.6 km Moawhango-Tongariro Tunnel section of the Tongariro Power Development Scheme in New Zealand gave rise to severe operating problems, particularly in the equipment stripping stage when pumping installations had to be removed. Due to the necessity to commence stripping from the upstream side the contractors. Codelfa-Cogefar (NZ) Limited, took the decision to install a steel bulkhead some 5000m in from the lower. Tongariro, portal. The article lists the considerations taken in the placement of the bulkhead, and gives details of its design, installation and final removal. A brief description of the geology of the tunnel. together with water flow sources, rates and pressures is also included.

Jan 1, 1981

By K. N. Han, K. Peri, Y. Guan

The leaching behavior of gold in ammonical solutions with iodine as an oxidant was investigated using cyclic voltammogram and Tafel polarization. The majority of the experiments were carried out at 75°C, and the results were compared with consideraton given to the equilibrium of the iodine-ammonia system. The distribution of nine iodide-containing species at various pH values in the absence and presence of ammonia were considered at three different temperatures. It was found that, with the introduction of ammonia into the system, the concentration of iodide (I-), iodine (I2) and triiodide (I3-) is increased substantially, which in turn helps the rate of gold dissolution. The apparent activation energy was found to be about 46 kJ/mole, indicating a chemical-controlled mechanism.

Jan 1, 2002

By J. A. Folinsbee

Placer Dome Canada owns and operates the Campbell Mine at Balmertown, in the Northwestern corner of the Province of Ontario, Canada. The mine operates at 1500 stpd and produces in excess of 300,000 oz of gold annually. Recent changes to the gravity concentration circuit have resulted in a 10-15 % increase in gravity recovery. The circuit changes responsible for these improvements will be the focus of this paper.

Jan 1, 1997

By A. W. Laughlin, C. R. Mansfield, M. J. Ferris, D. A. Cremers

Analytical costs are a major part of exploration programs in developing nations which may lack adequate laboratories. Laser-Induced Breakdown Spectroscopy (LIBS), a variant of atomic emission spectroscopy, can reduce exploration analytical costs and can provide the analytical results in <1minute. CPI is now marketing battery-powered, backpack mounted analyzers, using LIBS to analyze for many elements of interest to the explorationist. LIBS is well suited to the analysis of elements in industrial minerals. Limits of detection in ppm for some of these are: Li-1, Be-2, Na-100,B-33, Sr-10, Ba-300, Cs-1, K-500, Fe-500, Mg-500, andTi-500.

Jan 1, 1999

By William M. Gleason

The war in Vietnam stretched into another decade, an American President was at the brink of impeachment, the earth was given its own day, twin tower monuments of American ingenuity were completed in New York and would stand high above the Manhattan skyline for 31 years. Inflation, oil shortages, low commodity prices and America’s 200th birthday were part of the decade — it was the 1970s. For the mining industry, the demands of the decade would be high and the challenges would be significant. Because of the many challenges that lined up in front of it, the mining industry was forced to work smarter and more efficiently. The industry also expanded its borders in search of new resources and struggled along with the rest of the world through a fuel crisis, inflation and a recession.

Jan 1, 2007

By M. Albrecht

I have been following the discussions on coal degradation started by the article "Degradation process in coal slurry pipe-lines," by M.G. Ayat and B.C. Scott. I agree with Mr. Dasher&apos;s comments in January that the title of the article was perhaps misleading as the information appeared to pertain more to processing the coal than to transportation. Specifically, the authors&apos; conclude that the cyclone had an important impact on the degradation. Dr. Ferri&apos;s comments on degradation in other physical processes was very correct, handling of coal in a turbulent manner has an impact on the size distribution of the coal. This is one reason that when I design a coal system (mine to rail car) I try to minimize the total number of transfer and processing steps consistent with achieving the desired product specifications. Another area, mentioned in passing in the article, the impact of natural causes and the mining step, is of particular interest to me. A mine in West Virginia had a variation of 50% in the -6.35 mm (-0.25 in.) raw coal depending upon the direction of mining. Since it was a single unit mine, this significantly impacted the final product. Two articles on mining&apos;s impact on size distribution are: • Stefanko, R., Chopra, 1K., and Ramani, R.V., 1974, "Mining influence on size consistency and washability characteristics of coal," SME Fall Meeting, September; and • Albrecht, M., and Olsen, D., 1980, "Mining methods impact on coal preparation plant design," 1st International Mine Planning and Development Symposium, September. Both articles presented information on variation of size distribution and cleaning plant performance on a coal depending on the mining method used. Both articles considered a single coal seam at one mining operation. Stefanko&apos;s article considered continuous and conventional mining of coal in Pennsylvania. Albrecht&apos;s article considered surface, underground continuous, and underground hydraulic mining of a coal in British Columbia. Both concluded that mining methods do impact coal characteristics. I agree with Mr. Ayat&apos;s comments in reply to Dr. Ferri&apos;s discussion, "... degradation is a multi-faceted phenomenon involving many natural and man-made factors." As efforts are being made to produce a higher quality (lower sulfur) coal, this topic becomes even more important

Jan 1, 1989

By R. L. Lewis

A simple method for estimating the steady-state water quality of a pit lake is presented. The steady-state concentration of a conservative chemical constituent in a pit lake is shown to be a simple function of the inflow rate, the evaporation rate and the inflow concentration. An analytical method is presented for estimating the equilibrium ground water-inflow rate for use in water-quality predictions. The time required to reach chemical steady state is estimated using an iterative mass-balance model. Mine operators should find the methodology useful for planning and screening regulatory applications where conservative estimates of pit lake water quality are desirable.

Jan 1, 2000

By K. Komnitsas

This paper presents the main environmental assessment techniques and indicators that can be used a) for the establishment of a sustainable development framework and b) for the evaluation of the environmental performance within the mining sector. Reference is made to techniques as environmental risk and impact assessment, life cycle assessment, cost benefit analysis and best practical environmental option assessment that can be used as tools to assess environmental impacts of processes, activities and products in the mining sector. In addition, the issue of environmental indicators, covering operational, management and environmental areas, that provide valuable information regarding both the environmental performance of a mining company and its efforts to influence this performance towards sustainability is discussed.

Jan 1, 2003

By Bahne C. Cornilsen, X. Shan, David H. Carlson, John H. Johnson

The air in three U.S. underground coal mines has been sampled. The data developed show the relative importance of the various pollutants and quantify the need for control. Total respirable particulate matter (TRPM) was found to be the critical pollutant (the one requiring the most dilution for control). TRPM is considered to be "respirable coal dust" by procedures approved for sampling in U.S. underground coal mines. However, this "respirable coal dust" also includes diesel particulate matter (DPM) and particulate from other sources. While "respirable coal dust" was the critical pollutant, Raman spectroscopic analysis showed that more than half of this "respirable coal dust" was DPM. The DPM in the samples ranged from 22 to 152% of the 2 mg/m3 limit for respirable coal dust. Thus DPM was the critical pollutant using the 2 mg/m3 respirable coal dust limit. SO2 gas produced by the combustion of diesel fuel containing sulfur was the second-most critical pollutant. Characteristic curve slope (CCS) values were calculated to determine the quantitites of the various pollutants generated per unit of diesel haulage activity. Mine 1 had the highest TRPM CCS values with 29 mg/m3/%C02 for the Ramcar and 57 mg/m3/%C02 for the Haulageway location. The highest coal particulate CCS measured was 30 mg/m3/%CO2 and the highest diesel particulate CCS measured was 27 mg/m3/ %C02. Both of these high values were measured in the Mine 1 haulageway location. Calculations were made to determine the controlling CO2 concentrations (CCC) at which all other measured pollutants would be within their limits. These CCC values, which, for the mines sampled, were based on TRPM, varied from a low of about 0.07% for the Mine 1 haulageway location, to a high of about 0.15% for the Mine 2 Ramcar and haulageway locations. Weekly average CO2 concentrations measured in these mines ranged from 0.09 to 0.11 % for the Ramcar, from 0.05 to 0.09% for the haulageway, and from 0.08 to 0.11 % for the return. The concentrations of TRPM ranged from 1 and 2 mg/m3 in mine areas frequented by personnel, and to greater than 4 mg/m3 in returns where personnel are not exposed.

Jan 1, 1991

By Zhang Zhitie

The limitations in mechanism research of mineral comminution in the past and the basic features of the comminution process have been analyzed. Two kinds of catastrophe model, i.e., cusp model and swallowtail one in the mineral comminution have been put forward. The dissipative structure of the mineral comminution: entropy production rate, extra entropy, extra entropy production and system stability has been discussed. The physical nature of the behavior that an old structure was destroyed and a new one was produced in the mineral comminution process has been brought to light.

Jan 1, 1995

By D. E. Hart, A. R. Walsh, Derek Maishman

In order to safely construct a ventilation and escape shaft through saturated overburden into an operating mine, artificial ground freezing and raise boring were combined for the first time on a project in the U.S.A. at Georgia-Pacific&apos;s Kentwood Mine in Grand Rapids, Michigan. Previous to drilling a pilot hole 206 feet deep into the mine, a 20 foot diameter cylinder of soil 140 feet deep was totally frozen. Before termination of the freezing operation, the pilot hole was reamed to 9 foot diameter and a 7 foot inside diameter hydrostatic steel liner was grouted in place.

Jan 1, 1991

By Geoff C. Knight

Longwall mining using the shearer is acknowledged internationally as the most economically successful method of high volume production from underground coal mines. Since its introduction in the 1950s, a great deal has been achieved in developing the capability and reliability of the shearer - and the associated face conveyors and powered roof supports - to produce the competent systems now widely deployed. Equipment will continue to improve as knowledge and experience are gained and through the influence of market forces on the international equipment suppliers. However, current systems are so successful that further improvements are likely to be incremental rather than radical unless a high level of system automation is introduced. The automation concept is not new to the shearer-based longwall system. The opportunity and the need were recognized soon after the shearer and powered support were introduced in the 1950s. In the early 1960s, the British Coal Corp. (BCC; then the National Coal Board) attempted remotely operate longwall systems. Those imaginative early schemes were seen as failures at the time. But, with hindsight, a great deal was learned from the experience that stimulated automation research in several European countries. One of the most fundamental lessons learned was that coalface system automation is not possible until there is a high level of competence in automatically controlling the operation of the production machine itself within the coal seam. Once that is achieved, the rest of the system will follow with comparative ease.

Jan 1, 1991

By Risto Lindsberg

A wide concept of flotation equipment and technologies is presented in this paper. The basis for the presentation in Outokumpu&apos;s world-wide experience in mineral processing and other related areas, and continuing research and development work done in Finland as well as abroad by Outokumpu&apos;s subsidiaries (and customers). It is understood that flotation equipment selection for a certain process stage is becoming more complicated. It is obvious that flotation equipment in grinding circuit needs different design from a multistage cleaning process. In this paper, column flotation is compared with other flotation methods. Thus three areas of flotation are discussed in this paper: 1. Flotation in the grinding circuit, Skim-Air machines 2. Rougher-scavenger flotation, conventional cells vs columns 3. Cleaning flotation, columns

Jan 1, 1988

By Jeff Schwoebel, Dale Evans, Boyd Tangren

The Soldier Canyon Mine (the "Mine") degasification project demonstrates the ability to commercially recover coalbed gas to reduce overall mine costs associated with methane drainage. Gas is recovered from active and inactive areas of the Mine through an underground pipeline and surface compressors. Close inspection of gas quality is required due to potential contamination of air caused by excessive vacuum. Water must be removed routinely to enhance gas removal. This paper will review the operational and production procedures required to maximize gas recovery and insure safety at the Soldier Canyon Mine gas recovery project.

Jan 1, 1993

By Russell Barr, Robert E. Cook

As most mining companies are taking advantage of the high market prices for base metals such as steel, copper and zinc, numerous challenges still face them. While demand is strong from countries like China and the United States, demand is still mixed in Europe. This leads to the question of how long these high prices and overall high global demand will last. The tremendous market prices of most precious and base metals have enabled many companies to pay down a significant amount of debt accrued during acquisition and capital expenditure phases. Additionally, mining companies have been able to internally fund and engage in large projects to address future growth, (Less, 2006), thus maximizing the performance of the existing asset base, driving maintenance costs down, and improving and empowering the work-force (Mining Journal, 2006). Market prices and general efficiency gains have addressed these issues to some extent. However, critical issues still face operating managers in the mineral pro-cessing side of the industry. Energy prices, for example, continue to have a negative impact on cash costs for producing an ounce of gold or ton of a given base metal (Cummins, 2003).

Jan 1, 2007

The transfer of Langmuir-Blodgett (LB) monolayers of collector molecules to the surface of mineral crystals is an excellent method for the study of collector adsorption phenomena and is of particular significance in the understanding and development of improved flotation separations. The fatty acid/fluorite and amine/sylvite potation systems were investigated by the Fourier transform infrared/internal reflection spectroscopy (FT-IR/IRS) examination of transferred LB monolayers of collector molecules at the surfaces of the mineral crystals. The [ir]-A isotherm study of fatty acid and amine, typical anionic and cationic collectors, showed the different packing trends dependent upon the pH and/or type of subphase. This result clearly reflects the effect of pH on compound formation and dissociation of the collector molecules. Identification of the collector adsorption state and confirmation of the validity of the FT-IR/IRS adsorption density equation were included in this research effort. This allowed for a detailed discussion of collector adsorption phenomena. As a result of these experiments, it is possible to relate the hydrophobic character of a surface to the nature of the adsorbed collector structure and thus describe flotation behavior in greater detail. For example, it appears that in the case of oleate/ fluorite the equivalent of an LB monolayer can form spontaneously during adsorption from solution, and this structure is known as a self-assembled monolayer (SAM). Such a state is significantly more hydrophobic than the oleate structure which forms on the calcite surface at an equivalent adsorption density.

Jan 1, 1996

Canada is a major producer of chrysotile asbestos. In fact, Canada accounts for approximately one third of the world chrysotile asbestos production. Deposits are mined and the fiber processed in Québec, in British Columbia on the West Coast and in Newfoundland in the Atlantic region. Foremost among the Canadian provinces is obviously Québec. Some 85% of Canadian deliveries come from mines located in the Eastern Townships, a region which lies along the southshore of the St. Lawrence River, between Montreal and Québec City. At the heart of this vast territory, five (5) mining towns make up what is called the Québec asbestos region. Total capacity of the five (5) mining producers of Québec is about 1 366 000 tonnes.

Jan 1, 1981

By Kenneth K. Humphreys

27.1-HISTORY, PROCESSING STATISTICS KENNETH K. HUMPHREYS 27.1.1-MINERAL PROCESSING HISTORY The processing of minerals predates recorded history. Many processing techniques have existed for thousands of years. For example, Georgius Agricola, in De Re Metallica (1556), described equipment and techniques, such as picking tables, smelting furnaces and cupolas of various types, sieves, launders. various types of crushers and grinders and other equipment, all still in use in one form or another. In translating Agricola&apos;s work into English, the late Herbert C. and Lou Hoover provided the following summary indicating the early history of particular mineral- processing operations :

Jan 1, 1973

By J. Allen Hennessy

INTRODUCTION The increasing price of gold and silver over the past 10 years has caused increasing activity in the exploration, evaluation and development of precious metals projects. Many of these deposits are relatively low grade and short lived which makes them economically sensitive to the major project variables such as metal price, capital cost, operating cost and of course, tonnage and grade. These deposits often have a high variability (a coefficient of variation -- o/u -- of 2 to 5) and an intermixing of ore and waste, making ac- curate ore reserve estimation difficult, especially when using traditional estimation techniques. Often, the estimation errors are not the 10-20% that we see in base metal deposits, but the errors in grade and tonnage can be as high as 50%, which can obviously have a very substantial impact on project Recent developments in geostatistics when coupled with a sound geologic under- standing of the deposit can significantly improve reserve estimates of these variable precious metals deposits. Examples will be given of actual deposits where the traditional estimates were significantly different from the mining reality. An attempt will be made to explain the applicable geostatistical tools with a minimum of geostatistical jargon and without complicated formulas. The key to improving the reserve estimates is a clear understanding of the deposit geology and especially the structural controls, the use of local estimation techniques that recognize the intermixing of ore and waste and the effect of selective mining on recoverable reserves, and the use of a global reserve estimation technique to check the results of local estimation. Geologic Controls The vast majority of gold and silver deposits being mined or developed in the western United States would be classified as epithermal deposits. These are formed by hydrothermal fluids (hot water) flowing upward through the rocks and depositing the precious metals as the fluids cool or reach areas of lower pressure or favorable chemical sites. These environments are similar to present day hot springs-type environments with some deposits being clearly associated with surface hot springs such as the Homestake McLaughlin deposit in northern California. These hydrothermal deposits can occur in sedimentary rocks resulting in deposits such as those of the Carlin district or the Jerritt Canyon deposit or the hydrothermal systems can occur in volcanic rocks forming deposits such as Round Mountain, Manhattan or Paradise Peak. The mechanisms of formation were similar in either case with the solution flow controlled by geologic structure and precious metals deposited when the conditions of temperataure, pressure and chemical environment were favorable. The gold and silver hearing solutions travel through permeable faults and fracture systems depositing the metals along these channels. The grades are often highest in the central parts of these conduits (veins) with lower grades in the surrounding rocks. An understanding of the nature, distribution and orientation of these plumbing systems is important to a realistic reserve estimate. The point to be emphasized here is that, good, sound geology in the form of geologic mapping, logging of rotary chip samples and a few carefully logged core holes can signifi- cantly improve an ore reserve estimate.

Jan 1, 1987

By Martha S. J. Leary, Malcolm J. McPhersqn

This paper introduces a computer simulation which extends the utilization of microcomputer systems for mine ventilation planning. The program was developed as part of an ongoing study to produce a simulation model that would determine the optimum duties of a main fan and a booster fan without requiring the trial and error runs that are necessary with currently available programs. To use the new program, the user specifies the location of one main fan and one booster fan, and the minimum required airflows in any number of working places. The computer deter-mines the fan duties that will maintain the required airflows at the lowest operating costs without causing undesired recirculation. The methodology of the program and an example showing how it can be applied are presented.

Jan 1, 1988