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By Robert A. Cortese, Carrie E. Lucci

Mine Safety and Health Administration (MSHA) regulations require underground coal mine operators to dust their mine corridors with an inert material to prevent coal dust explosions. The most commonly used material is pulverized limestone. Current practice to determine compliance with MSHA regulations requires the coal mine foreman or an MSHA inspector to collect samples of the deposited dust, a mixture of coal dust and limestone rock dust, for above ground laboratory analysis. To expedite this process, the U.S. Bureau of Mines has developed two instruments to facilitate the inspection and rock dusting processes, the explosibility meter and float dust deposition meter. The explosibility meter is a hand-held instrument which provides an in situ measurement of the explosible nature of homogeneous mine dust samples. The float dust deposition meter measures the mass loading density of the top layer of coal or limestone dust deposited on the mine floor during mining operations by the ventilation air. It may also be used to automate trickle rock dusting equipment. The operation of each device is based on the difference in the optical reflectance between the light limestone dust and the dark coal dust. The principal of the explosibility meter is based on the observation that, for a fixed coal volatility, the optical reflectance of dust mixtures is relatively constant at the limit of flammability, and independent of the coal dust particle size.

Jan 1, 1995

By D. W. Wu, M. T. Haque

A novel impedance probe was commissioned specifically for capturing fast dynamic information about filtration processes. It provides an attractive alternative to more complex measurement techniques in situations where the slurry system is primarily one-dimensional. The probe can monitor mudline, slurry densification and drainage. Dynamic variations in cake permeability are obtained by combining dynamic mudline information obtained with the probe and filtrate rate data derived from a leaf test apparatus. The measurements are reviewed in relation to micro structural measurements obtained on iron ore filter cakes. The practical significance of these measurements for optimization of the filtration process is discussed.

Jan 1, 2002

By T. Schrauf, J. Scott

"INTRODUCTION Cyanide heap leaching of gold ores in areas with extremely low winter temperatures requires special considerations to prevent freezing of the leach solution. Factors that impact the solution temperature include ore temperature at the time of stacking and during operation, burial of drip irrigation lines, use of geomembrane covers, and heating of the leach solution. Thermodynamic modeling was performed to simulate expected ore and solution temperatures under different operating strategies for Kaminak Gold’s Coffee Gold project in the Yukon Territory. Mean monthly temperatures at the site ranged from a low of -22.5oC to a high of 13.6oC, while in situ ore temperatures ranged from -0.5 to about -1.5oC. The modeling results were used to optimize the operational parameters and indicated that a combination of drip line burial and heating of the leach solution during the winter months was required to maintain solution temperatures above freezing during the initial years of stacking, although as the size of the heap increased, heating was no longer necessary. MODELING OBJECTIVES The successful operation of a cyanide heap leach under extremely cold winter temperatures requires the implementation of operational strategies to prevent freezing of the leach solution and the ore within the heap. Thermodynamic modeling of the heap provides the means to quantify the effectiveness of these different operational parameters on maintaining the required operating temperatures to avoid freezing within the heap. The operational parameters that were evaluated with the model included: • Burial depth of irrigation lines to prevent freezing during the winter months; • Variation in the temperature of the applied leach solution (to simulate heating of recirculated solution); • Variation in the rate of irrigation including seasonal variations between winter and summer months; • Seasonal versus year-round stacking of ore (to simulate the impact of the initial temperature of each ore layer as it is stacked); • Seasonal versus year-round crushing and stockpiling of ore, including the option to stockpile ore on the leach pad in the winter (i.e. stack but not leach fresh ore in winter); • Start date for seasonal stacking; • Variation of the heap geometry over time (both vertical and lateral expansion) and the associated heat storage within the heap; • Use of thermal covers (gravel or geomembrane) over the ore during the winter months; and • Effect of crush size on heat loss during crushing, stockpiling and stacking."

Jan 1, 2016

By J. A. Frew, G. I. Orrock, R. M. Glen

The zinc flotation circuit was sampled to provide sized information on its metallurgical performance. A good balance was obtained and the roughing, scavenging, cleaning and regrind sections were assessed. Substantial losses of sphalerite occurred in all sizes. The limitations were poor recovery in the cleaning section which resulted in substantial recycling of 15-30µm sphalerite and iron sulphides, and inability to float +38µm sphalerite in the roughers. Regrinding increased sphalerite recovery by 7% with no loss in grade. Liberation measurements enabled balances for six size fractions to be calculated and the role of liberation on the metallurgical performance was assessed.

Jan 1, 1993

By M. E. Smith

Chile is the world's largest copper producer and as such sets the standard of practice in copper SX/EW design. The authors summarize the liner systems used at many of Chile's major copper producers both operating and planned. The evolution in the state of the art is also discussed, considering both economic factors and Chile's burgeoning environmentalism.

Jan 1, 1994

By Manfred Jaeger, Klaus Ertmer, Walter Dietrich, Jochen Greinacher, Wilhelm J. Kogelmann

In Europe, novel low-cost excavator-mounted Multi Tool Miner (MTM) systems, consisting of cutter head, hammer, bucket and drill attachments permit one unit to perform multiple tasks replacing several purpose-built machines. At the Weser Tunnel in Germany, cross-passages between the twin tubes were excavated in frozen ground with a remote-controlled mini-excavator equipped with a quick-change cutter head, ripper tooth and bucket. In Switzerland at the N2 interstate near Basel, W. Dietrich AG enlarged a 2-lane tunnel to three lanes with a cutter head mounted on a special excavator. Blasting and heavy hammers were not permitted due to the closeness of the “live” twin tube. At the N20 Zurich bypass, the Joint Venture of Jaeger, Frutingerand AHB excavates highway tunnels, some with extremely large cross sections, conventionally. A cutter head mounted on an excavator removes the rock shattered by blasting precisely to the pay line, thus preserving the rock’s self-supporting capacity preventing subsidence and damages to water resources and buildings on the surface under low overburden.

Jan 1, 2003

By Robert A. Jankowski, Ellsworth R. Spencer, Jay F. Colinet

Longwall mining is the most productive method of under- ground coal mining in the United States (US.), and record levels of production have been reached in recent years. These ever-improving production levels have the potential to generate significantly higher quantities of respirable dust. Consequently, the longwall industry continues to struggle with controlling dust liberation and maintaining compliance with the federally-mandated respirable dust standard. In response, longwall operators have in- creased the application of primary dust controls, airflow and water flow, in an effort to improve respirable dust control and reduce worker exposure. Pittsburgh Research Center (PRC) personnel conducted dust surveys at 13 longwalls operating throughout the U.S. and collected information to: identify current operating practices on these longwalls, identify the types of dust controls in use, document the levels at which these controls are being applied, and measure the respirable dust levels present. This data was analyzed to quantify the dust levels generated by the major sources on the longwall section and to evaluate the relative effectiveness of the control technologies in use.

Jan 1, 1997

By Stephen J. Brower

Located in Central Nevada, The Round Mountain Gold deposit has been continuously mined since 1977. Present proven and probable reserves are 226 Mt (250 million short tons) at 1.1 g/t (.032 oz per short ton). The current open pit mining rate of 118 Kt (130,000 short tons) per day is producing 41 Kt (45,000 short tons) per day of ore to be processed by heap leach methods. At this rate, the current reserves provide a 16 year mine life. The high mining rate and strict ore delivery requirements mandate comprehensive and realistic mine planning. The mine planning process is described in three general steps: Deposit Modeling; Mine Design; and, Production Coordination and Support.

Jan 1, 1989

The sixth annual conference of the Mineral Economics and Management Society (MEMS) was held Feb. 27 through March 1 in Boulder, CO. This year's event was attended by more than 100 academic, industrial, government and other professionals interested in mineral economics and materials management. With about 250 members worldwide, this not-for-profit society seeks to promote scientific and economic analysis of current relevant issues. This year's program was sponsored by Alcan, Bateman Engineering, Cyprus Amax Minerals, J.P Morgan, Knight Piesold LLC and Newmont Gold. The conference's technical program consisted of six sessions. These included "Financial tools for a changing world," "Access to minerals," "Comparing North and South America," "Environmental issues in today's world" and "Transporting minerals." The program was concluded with a panel discussion titled "National minerals policies in Asia." In addition, a student papers session was held, in which students were given the opportunity to compete for a $1,000 award. The following is a brief review of the technical pro¬gram.

Jan 1, 1997

By R. Hogg, E. Kaya

The presence of agglomerated particles in airborne dust in coal mines has been confirmed by SEM examination of static samples collected on substrates. In addition, the effect of agglomerated particles on the performance of cascade impactors and cyclone- type personal samplers has been studied. Simple procedures have been developed for evaluating the extent of agglomeration in air-borne dust by comparing the observed size- selectivity of the sampling devices with that expected under idealized conditions. Applications of these techniques in the laboratory and in underground mines are discussed.

Jan 1, 1992

By Robert J. Gorney

This paper deals with the actual application of a direct digital control to simple as well as complex industrial process control loops, Fundamental descriptions of preliminary research and design are described briefly, as is the development of the present day controller and control computer. The results and effects of direct digital control in various types of single and cascaded loops as opposed to the use of conventional controls are discussed. Computer supervision of a process and control override are taken into account, in addition to methods of short and long term plant economic optimization.

Jan 1, 1965

By J. J. Komadina

Since the advent of resin-in-pulp (RIP) technology for treatment of uranium-bearing ores in the 1950?s to current carbon-in-pulp (CIP) processing of gold values, metallurgies and operators alike have wrestled with the problem of interstage screening. Early gold CIP plants such as at Homestake utilized externally mounted vibrating screens in conjunction with air lifts to effect carbon-pulp disengagement. Other operations world-wide have likewise adopted this technique with varying degrees of success. Subsequent development of in-tank launder screens both in South Africa and the United States have been of the air cleaned variety (EPAC)

Jan 1, 1988

By F. L. Wilke

Underground mining is a very complicated and complex industrial activity. The uncertain and, in most cases, the incomplete knowledge of the geological and mineralogical nature of the deposits can cause unforeseen difficulties. For a safe and uninterrupted operation, in addition to good planning and scheduling, reliable and up-to-date monitoring and control of all processes and conditions become necessary. Today, this is even more important in view of increasingly difficult working conditions, poorer grades, and more complex and expensive machinery. In short, large capital investment and higher risk of financial losses are involved in modern-day mining operations. Monitoring and control of the underground mining process has become a very complex and difficult task in itself. Many different systems are available, and the correct choice .is of utmost importance from both the economic and safety points of view. This chapter will deal with aspects of underground production monitoring and control. There are, however, many other areas of equal importance which are covered in an excellent manner in a hand- book by Olaf (1976) on monitoring and control of underground operations.

Jan 1, 1979

By H. E. M. N. Moursy, M. N. Ahmad, C. R. Holland, G. M. Walker, R. D. Chandler

This work describes the effect of process parameters on the acidulation of Moroccan phosphate rock using nitric acid, i.e., the nitro-phosphate process. A series of bench scale experiments were conducted, using a stirred tank reactor (STR) system, to investigate the chemical reactions involved and optimum conditions for the formation of nitro-phosphate fertilizer. The effect of reaction time, temperature, mixing speed, acidulation ratio, and acid concentration were investigated, and were found to have an effect on the dissolution of P2O5 from the phosphate rock, using nitric acid. An increase in nitric acid concentration resulted in an increase in P2O5 dissolution, however, the dissolution was also found to be a function of acidulation ratio. A nitric acid phosphate rock ratio of 4:l ensured 90% dissolution for nitric acid concentration > 30%.

Jan 1, 2002

By Knezicek Zeljko, Knezicek Tihomir

Lignite open cast mine "Dubrave" is the largest lignite mine in Bosnia and Herzegovina. The open cast mine was designed with two external waste dumps. Waste dump "West" is the major dump, while "Cajici" dump is used for dumping waste taken from leveling the terrain. The major waste dump contains 14.6 million cu.m. of waste, while the side waste dump contains 3 million cu.m. of waste. Existing situation with available sites for depositing the waste shows that additional space for dumping the waste must be provided. Three options can be taken into consideration. The fact is that none of the three options are suitable for the current production situation. This article deals with the optimization process for obtaining the optimal variant where a waste dump can be located and selection of the most valuable option.

Jan 1, 2002

By D. W. Fuerstenau, P. C. Kapur

A new method is proposed for measuring the grindability of solids and the energy efficiency of grinding mills. The method is based on a similarity law of fracture mechanics for elastic materials in conjunction with the self- preserving character of the size distributions formed when feed particles are comminuted individually in compression. The single-particle grindability index reflects more closely the inherent resistance of a solid to size reduction than the grindability indices currently in vogue. The performance of grinding mills is evaluated in comparison with the single-particle breakage mode, which has the highest energy utilization or efficiency of all mechanical grinding routes. For a given set of stipulations, the performance index of the commonly used ball mill when grinding dolomite is found m he only 21%. compared to 44% for the high-pressure roll mill, a newly-invented energy-efficient mill. The difference is also reflected in the energy consumed per unit mass offines produced when closed-loop grinding circuits are simulated, which shows that the high-pressure roll mill circuit is invariably more energy-efficient than the ball mill circuit, provided the energy input per pass through the mill does not exceed a prescribed limit. Theoretical upper bounds on the yield of the ground product in a desired size range and lower bounds on the energy investment are calculated from the single-particle breakage mode which has, apart from the highest energy utilization efficiency, a minimum dispersion in size of the comminuted particles. Data on theoretical hounds for seven minerals/ores are presented. It is argued that it is unlikely that a grinding mill can be designed and a comminution circuit constructed whose performance exceeds these bench-mark values.

Jan 1, 1995

By Brain W. Lawrence

Sublevel stoping generally is a large-scale open stoping method. It sometimes is referred to as long-hole or blasthole stoping. This method usually is applied to strong ore bodies that require minimal support and are surrounded by strong country rock. The ore body should be fairly regular in shape and well-defined. The dip of the footwall normally should be sufficient to allow broken ore to gravitate freely, although the method has been adapted successfully to mine some of the flatter ore bodies. Sublevel stoping is not dependent on the width of the ore body. Widths of less than 6 m (20 ft), however, make the utilization of long-hole drilling techniques more difficult. The main criteria for sublevel open stoping are competent ore and stable host rock, regular ore boundaries, and a footwall dip that exceeds the angle of repose of broken ore. Basically, the method entails providing access to the ore body at various subintervals between the main haul- age levels in order to drill and blast the intervening ore. Stope drilling is carried out from drilling drifts on the sublevels, and the ore is blasted in slices towards an open face, which generally is vertical on the downholes and may be inclined towards the open face for the up holes. The blasted ore gravitates to the bottom of the stope and is collqcted through drawpoints. Fig. 1 illustrates a typical sublevel stoping mine. The method requires extensive ore body development with relatively high capital expenditures. How- ever, much of the development is in ore, and production costs are comparatively low. Productivity rates are in the 13.6 to 27.2 t (15 to 30 st)/manshift range. The drilling, blasting, and loading operations are performed independently, and equipment utilization is high. Large outputs can be obtained with few units and limited personnel. Dilution with waste rock may occur if ore boundaries are irregular or if caving occurs, but 100% of the ore within the stope usually is recovered. Pillar recovery sometimes is a problem. It is at this point that most of the waste dilution occurs. At the time data was gathered for this report (1973), the sublevel open stoping method was used by more than 21% of the metallic ore mines in the US (9 out of 42 mines producing 1088 + t/day (1200 + stpd) and provided more than 12% of the total metallic ore production from these mines. DEVELOPMENT Access to a sublevel open stope mine is gained by a slope or shaft that is normally sunk in the footwall of the ore zone, away from any possible effects from blasting or other production operations in the stoping process. Main level interval is selected and usually varies from 45.7 to 121.9 m (150 to 400 ft), depending on the vertical extent of the ore body, the number of drawpoints required to maintain output, and the eventual stope height. The main haulage drifts are located at the bottom of the stope horizon, either directly in ore or in the footwall, with access crosscuts at intervals. Raises are driven up through the ore to connect to the level above and provide access and ventilation to the sublevel drilling drifts, which are driven horizontally in the ore for the length of the stope. Depending on the drawpoint system to be used, the stope is either undercut by a raise-and-cone system, from a scram or slusher drift, or simply provided with a drilling drift from which access is made at intervals to the main haulage level. A raise driven either at the end or in the middle of the stope (if stope access is from both ends) provides a start for opening up a vertical slot across the stope to establish a free or open face for long-hole drilling and blasting. Sublevel stoping has proved to be a relatively safe and economical system.

Jan 1, 1982

By Charles N. Speltz

The cost of transportation of industrial minerals frequently is higher than the cost of the product. When a mine, industrial-mineral plant, or customer is served by a single railroad, because of the lack of competition, that railroad may in- crease rates and/or reduce service so that the economics of that mine, plant, or customer are affected adversely. Transloading of industrial minerals from rail-to-truck or truck-to-rail to improve economics and sales of product is not a new concept. However, transloading to create competition and reduce freight costs or to improve service is a relatively new concept brought on by the recent mergers of many of the main-line railroads, both in the eastern and western United States. For example, in 1998, with completion of the Burlington Northern/Santa Fe (BNSF) and the Union Pacific/Southern Pacific mergers (UPSP), the western United States has only two main-line railroads. The industrial-mineral producer, to reduce the cost of transportation or increase the level of service, must evaluate potential transloading opportunities in light of higher prices and reduced service brought on by reduced railroad competition. This paper discusses industrial-mineral transloading and examines the case history of the Tucker Hill perlite project in southern Oregon. The Tucker Hill project is a classic study of industrial-minerals transloading where the project would have failed without the transloading.

Jan 1, 1999

By R. Latifovic

Assessment of the possible impact of existing and future mining projects located in remote areas may be difficult and costly. This may have an adverse effect on the process of issuing mine permits and development of new mines. A remote sensing based land cover change assessment methodology presented in this paper is a promising avenue to render this process more meaningful, precise and affordable. It has been applied to a case study of the Oil Sands Mining Development in the north-east of the Canadian province of Alberta. Recently, the Athabasca Oil Sands Region (AOSR) is a place of unprecedented growth of open-pit mining operations. This study was focused on the primary impact onto the landscape and vegetation resulting from exploration and, mining development. This impact was assessed using an information extraction method applied to two LANDSAT scenes. The analysis based on derived land cover maps shows a 8.64% decrease of natural vegetation in the study area (715,094 ha) in 2001 relative to 1992. It is demonstrated that the methodology presented here provides reliable results and is fully applicable for the assessment of the environmental impact of large scale mining operations.

Jan 1, 2006

By Deepak Malhotra, William F. Riggs, Edward C. Dowling

INTRODUCTION Mining companies are In the business of making an acceptable profit on their Investments, It became obvious in the recent recession that economic profitability/viability depends on being the lowest cost producer In order to compete on a global basis. The burden of achieving this objective falls on the mineral manager. He must strive to produce a salable product in an environmentally acceptable process while continuously Improving the profit margln.(1,2) Metal prices fluctuate on a regular basis. They directly Impact revenue and hence operating philosophy. The mineral engineer needs to develop an optimum operating strategy to meet his overall objectives, One would expect that, In the modem era of complex computer models, it would be easy to develop an economic model to maximize profits and/or cash flow. Discussions with mill managers Indicate that one mine/corporation's optimum operating strategy is not necessarily optimum for another. This paper approaches the problems from basics "Economics 101" and Illustrates the complexity of developing a universal model which can be applicable to all mines. Case examples are used to illustrate the need for better communication to avoid the basic economic fallacy “that optimization of segments leads to optimization of the whole system.” TECHNICAL MODELS Technical models are a prerequisite to the development of economic models because they provide the necessary Input data to these models, The flow of material from a mine through the sale of the finished product is shown In Figure 1. The ore Is mined and milled, and the concentrate can be stored for sale or smelted and refined In-house or at a toll facility. The finished product(s) are held In Inventory until sold either through existing contracts or in the spot market. [ ] Fairly reliable technical models have been developed for mining, milling and smelter operations. Mine plans are developed to provide a good Indication of the relationship between production and cut-off grade. It is easier to change surface mine plans than plans for underground mines. However, there are limits to maximum production that can be achieved with existing equipment. It Is possible that mine benches may not be developed to handle additional equipment, even If It was purchased to enhance production. More often than not, the cut-off grade Is lowered to Increase throughput goals.

Jan 1, 1993