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By Andrzej Wala

Constantly increasing demand for energy materials and metal ores brought about tremendous progress in mining techniques which are characterised by a high degree of mechanization and concentration of works. One of the recent trends in underground mining mechanization is connected with an application of heavy machines with diesel engines [l],[2]. The introduction of diesel engines in mining all over world caused not only improvement in economic conditions but also the necessity to prevent contamination of air in the mine by toxic agents in diesel exhaust emissions. A generally used way of eliminating exhaust gases is proper ventilation of the cross cut by means of providing permanent exchange of air that would guarantee in every point of the cross cut and in every moment the decay in concentration of exhaust gases beyond threshold limit [3][4][5][6][7][8][9][10]. The present paper is an attempt to define a mathematical model describing the changes of concentration in cross cut face to which fresh air is distributed by ventilators and tubes in a forcing way. Obtained model should offer its practical adaptability to engineering calculation of the amount of fresh air needed for diluting and eliminating exhaust gases beyond threshold limit. Justness of these models has been confirmed by investigation of the growth of nitrogen dioxide concentration in air environment in some cross cut faces of Kiirunavaara iron ore mine in Kiruna (Sweden).

Jan 1, 1980

By M. J. Laurila

The concentration of low grade iron ores to pellets or sinter fines suitable for blast furnace feed or direct reduction is highly energy intensive and costly in terns of both size reduction and separatory processes. Large equipment with high throughputs are required to make the fine grinds and multi-stage separations economical. Control of these circuits is essential to producing a high grade product. As a result, iron ore concentrators possess some of the more sophisticated instrumentation for process control in the mineral dressing industry. These instruments must characterize flowstreams of up to 8,000 gpm where 80% of the particles are less than 50 µm. The past decade has been one where enormous strides have been made in automated control of iron ore plants. This paper reviews state-of- the-art control systems for crushing, grinding, magnetic separation, froth flotation and sizing/classifying circuits. Trends toward computerization and plant automation in response to a dismal outlook for North American steel production are also examined.

Jan 1, 1984

By Charles S. Spirakis

The consistent occurrence of organic carbon early in the paragenesis of Mississippi Valley-type sulfide deposits suggests a genetic link between organic carbon and the sulfide ores. Reduction of sulfate in the mineralizing solution by organic carbon at the sites of mineralization is commonly proposed as the precipitation mechanism for these deposits, but inorganic sulfate reduction is too slow to be important to the chemistry of the ore zone, and bacteria, which catalyze sulfate reduction at low temperatures, are not known to survive at the temperatures of mineralization. Sulfate reduction with or without bacteria is not consistent with the sulfur Isotope evidence. Sulfur isotope studies also indicate that the derivation of sulfur from hydrocarbon at the sites of mineralization is unlikely. Organometallic complexing may be involved in the transport of metals, but no plausible mechanism for breaking these complexes at the sites of mineralization has been proposed. Reduction of partly oxidized sulfur species in the mineralizing solution by organic carbon at the sites of mineralization is a possibility which deserves further scrutiny.

Jan 1, 2013

By Marcel Haffen, Jean Janin

The purpose of grouting is to modify the permeability and strength characteristics of the subsoil in such a way that the planned structure can be efficiently constructed at a given location. This technique, which originally underwent considerable development in the field of dams construction is constantly evolving and it becomes more and more important in urban zones of intensive underground development for projects such as transport tunnels, stations, car parks, ect. Grouting becomes more and more indispensable whatever the natural characteristics of that subsoil ; such is the case particularly when the planned work runs through cohesionless granular soils, usually water-bearing such as alluvium, sands, disturbed ground, fill material, etc. The selection of the grouting method and the extent of treatment required at depends on two fundamental factors. 1º) nature and behaviour of subsoil to be treated. There is no need to stress the necessary of a good knowledge of geotechnical, hydrological and chemical characteristics of the ground to be treated. At the present time the specialists in these fields have available numerous methods of analysis, either laboratory or field tests, which enable to evolve a suitable treatment.

Jan 1, 1997

By S. Frimpong

The coal mining industry is an important sector of Canada?s economy. The cost of mining and haulage of coal in Western Canada is a major focal point when compared to inexpensive coal from Australia. Spot coal price volatility affect contractual price arrangements and this creates pressure on companies? profit margins and their competitive edge. In order to alleviate this pressure, companies may have to take short-term drastic measures that may hurt their strategic positions in the long-term. Companies must also create a mix of their products to ensure effective maintenance of profit margins given various quantity and quality constraints. In this paper the authors provide extensive analysis based on detailed probabilistic production systems for coal extraction and haulage in Western Canada. An optimization model is formulated for typical coal mining operations, processing and haulage from mine sites to the Vancouver Ports using linear programming algorithm. A stochastic model is also formulated to analyze the associated risks and uncertainties. These models are validated using data from five operating mines in Western Canada with varying quantity and quality products and uncertainties. The results show that the five mines studied have to produce between 180,000 and 2.10 million tonnes of metallurgical coal and between 70,000 and 2.16 million tonnes of thermal coal to enhance their profitability given the underlying constraints. The average expected probability of success associated with production capacities from these mines is about 66%. This results in a failure probability of 36%, which is extremely high under contractual arrangements. The results also show that management?s profit expectation of $83 million can be achieved at a zero percent failure probability. With a higher risk of failure of 10%, this expectation increases by 21% to $100.3 million.

Jan 1, 2011

By Robert A. Jankowski, Charles A. Babbitt, Natesa I. Jayaraman

Today, approximately 31% of underground coal mining operations have designated occupations or areas with more stringent (below 2.0 mg/m3) respirable dust standards in place. Many U.S. coal mines have been able to maintain compliance with very low dust levels, and the Bureau of Mines, in an effort to identify those factors contributing to low dust levels, completed a survey of twelve continuous miner sections which were able to maintain their dust levels at or below 0.5 mg/m3. The quantity and quality of face ventilation appeared to be the most important factor in controlling dust exposure. The results directed Bureau research towards identifying improved face ventilation techniques for reducing quartz dust levels on continuous mining operations. This research has involved the evaluation of a half-curtain face ventilation technique which reduces the cross-sectional area of the entry, thus increasing the air velocity over the operator. The Bureau has also conducted extensive laboratory studies to compare tubing versus brattice, including an evaluation of both systems in a crosscut turn. In an effort to improve ventilation and reduce dust exposures of roof bolter operators working downwind of the continuous mining machine, the Bureau has evaluated two novel face ventilation systems. The first system consists of a fan discharge tubing technique which routes dusty air away from the return entry being bolted. In a technique similar to the fan/tubing concept, exhaust air from the upwind continuous miner face can be scrubbed using a dust collector to capture a portion of the dusty air, clean it, and supply it to the bolter operators as a split of clean intake air. A better understanding of face ventilation techniques should lead to solutions to the problem of more stringent dust standards due to quartz.

Jan 1, 1989

By C. E. Jordan

The Bureau of Mines conducted research to measure the improvement provided by fine bubbles on the flotation of fine-sized particles (minus 20-um size) in an effort to improve flotation efficiency in our domestic minerals industry. The turbulent velocity distributions of the fluid within the flotation cell were measured as a function of time and position and used to increase the precision of a fine particle, turbulent flotation model. For the mineral system investigated, improved flotation response was obtained under laboratory conditions by using small bubbles and intense agitation. These results matched the model's predicted response.

Jan 1, 1989

By G. I. Voiloshnikov, V. E. Dementyev

Wide use of adsorption methods for metal recovery is one of the most important achievements of gold metallurgy of the last decades. Anion exchange resins or activated carbons may be used as adsorbents. This paper presents a brief overview of IRGIREDMET effotts on development, testing and implementation of techno­logical flowsheets using both adsorbent types and attempt to compare their technological properties. IRGIREDMET Institute was founded in 1871 as a laboratory for gold smelting and gold ore testing. In 1930 it obtained the status of the Research Institute. IRGIREDMET functioned as leading research center for gold mining industry in the former Soviet Union. At present it is the Open Joint Stock Company dealing with all s01t of research and design works for gold min­ing (ranging from geology to gold refinery). IRGIREDMET started development of ion exchange technol­ogy in 19641• The first stage of work (1964-1970) including development of principle flowsheet of RIP process was carried out jointly with the Moscow VNIIKHT Institute (All-Russian Scientific Research Institute of Chemical Technology)2• The flowsheet of RIP process is presented in Fig. I and includes the following basic operations: gold adsorption from pulp; washing of loaded resin; acid treatment; thiourea adsorp­tion; gold elution by acid thiourea solution; resin washing to remove thiourea; alkaline treatment of resin; resin washing and gold recovery from eluates by electrowinning. The technology developed and equipment used were tested for treatment of clayey ore of Kuranakh deposit at a pilot plant of the Lebedinsky gold complex ("Aldanzoloto" company, Yakutia, Russia). The pilot plant throughput was 200 t/day. At the same time IRGIREDMET conducted the tests on ion exchange technology for ore and concentration products of oper­ating gold plants and for ores of new deposits. Laboratory and pilot plant tests were done and developed initial data and process design criteria for designing of 15 plans of the former Soviet Union. In the course of this work a great number of newly synthe­sized anion exchangers including strong and weak base resins was studied, the peculiarities of anion exchange resins using two different raw material types ( ores and concentrates includ­ing clayey, carbonaceous, silver bearing, arsenic, antimony and base metals bearing products); some theoretical regularities of adsorption process were investigated; the technology of two stage adsorption of gold and silver from silver gold ore, improved flowsheet for gold elution and resin regeneration, design of adsorption equipment including pulsation columns, design of electrowinning cells were developed; conditioning technology for pulp with complex ion composition prior to gold and silver adsorption was developed, etc.3·8• IRGIREDMET specialists took part in commissioning of practically all the plants in the former Soviet Union using RIP and RIL process including Lebedinsky, Kuranakh, Sovetsky, Karamken, Matrosov's plant and Mnogovershinny plants. Due to this works RIP process became standard technology for Russia and the CIS.

Jan 1, 1998

By Jacek Kolacz, Knut Lyng Sandvik

Fine grinding in an air swept and a grate discharge ball mill working in closed circuit with a forced vortex air classifier has been investigated in continuous laboratory scale. Minerals with different physical properties were ground down to 40, 20, and 10 micron top size. The shape of the product particle size distribution curve was investigated and specific surface (BET) was measured. During production of material with top size of 40 microns in an air swept mill, the capacity was up to 25% higher when compared to a grate discharge mill. This difference dropped to 180A during production of 10 micron top size material. A corresponding decrease in power consumption was observed. An important finding is that by regulation of the air flow rate through the mill, it is possible to achieve products with different specific surfaces and particle size distribution curve steepness. During production of the 10 pm material, the specific surface could be varied in the range 3 to 4.5 m2/g. Such powders could hardly be produced in a grate discharge mill because fine particles coated the grinding media and the lining. On the other hand the internal classification in the air swept mill kept the size distribution of the mill content relatively free of fines. This prevented a similar slowing-down of the air swept grinding process.

Jan 1, 1995

By D. S. Choi

Underground production of coal by longwall methods has increased significantly in the last few years and will very likely continue to: increase. There are several reasons for this. First, as mining moves into seams having greater overburden, roof exposure must be reduced since support will become' increasingly expensive. Secondly, the growing demand for coal has forced the coal industry to seek alternative, more productive, coal mining methods. In addition, the longwall method greatly simplifies the underground ventilation network. This paper addresses itself to the design of longwall development headings, particularly to those of the United States where multiple development headings are required by law. The most burdensome problem encountered in many longwall mining installations is deterioration of the tailgate due to the combined effect from, the active longwall gob and the old gob made by mining the previous panel.1 Portions of the tailgate entry are sometimes closed to such a degree that extensive repair work is necessary to keep the entry in usable condition. The purpose of this paper is to present the result of a study in progress which combines field measurements with numerical model analysis to reduce the cost of maintaining tailgate entries in longwall mining systems.

Jan 1, 1975

By Larry Powell

Rend Lake is an Army Corps of Engineers reservoir located in Franklin and Jefferson Counties in south-central Illinois. The lake consists of 20,000 acres of water and 19,000 acres of public access land. The site attracts over two million visitors a year and is surrounded by campgrounds and other recreational facilities. The lake overlies the largest tonnage of low sulfur coal in the state. Coal is being removed beneath the lake from five mines operated by three coal companies. Currently high extraction mining operations are approaching low-lying, environmentally sensitive, and high-use recreational areas. Advanced planning to maximize coal extraction and minimize potential effects of subsidence requires the development of procedures to assess the impact of high-extraction mining on the land use of the area. The Bureau of Mines, the Corps of Engineers, and the coal companies have initiated research to assess the following proposed planning steps to ensure the maximum recovery of the coal resources while minimizing impacts to surface land use: 1) Establish a dialogue between the surface and mineral owners; 2) develop a geographic information system to aid in assessing existing land use and potential changes; 3) assess the potential effects of subsidence on drainage, wildlife habitats, and changes in land use prior to mining; 4) coordinate the mining displacements with surface activities to minimize disruption; and 5) develop appropriate mitigation plans before mining occurs.

Jan 1, 1986

By M. C. Stuttle

MDL Rock Lasers has undertaken successful mapping trials of abandoned mine workings using its underground cavity scanning system. The work was being performed for Kalgoorlie Consolidated Gold Mines (KCGM), Australia's largest gold producer. MDL Rock Lasers supplies underground surveying systems to the mining and quarrying industry KCGM's Fimiston Super Pit, located in Kalgoorlie, Western Australia, is Australia's largest open-pit gold operation. Fimiston's final pit design is expected to be 3.7 km (2.3 miles) long, 1.5 km (0.9-miles ) wide and 540 m (1,770 ft) deep. During the early days of Australian mining, underground operations were labor intensive. Mining was selective and generally narrow stopes were mostly backfilled. Improved processing technology and mine mechanization during the 1970s and 1980s has permitted larger scale operations to adopt less selective underground-stope operations. The "super pit" concept was a logical step for mining companies working toward economies of scale. However, the industry recognized that there was no precedent for excavating a 500-m- (1,640-ft-) deep open pit through ground previously affected by old workings. To appreciate the geotechnical challenge facing KCGM, it is necessary to consider that under the pro¬posed area at the open pit, stoping reached a level of 1 km (0.6 miles) and was supported by more than 2,000 km (1,240 miles) of development headings. The company was fortunate because plans were available for the Golden Mile underground operations. The existing plans were interpreted by the mine's geotechnical team and computer models were constructed of the underground workings. These models can be imported into three-dimensional mine planning packages, such as the Vulcan's Unix-based software, Envisage, to assist analysis and design. This prior knowledge of the workings provided the focus for investigating and confirming ground conditions using probe drilling. After several iterations of drilling, followed by detailed analysis, several decisions were made relating to the nature of the ground and the mining approach to be taken. It was recognized that the stope models were not perfect due to hu¬man error, lack of original survey information and progressive deterioration in ground conditions. It also became apparent that the sole reliance on probe drilling was inefficient in terms of time and quality of information. This was particularly true in complex areas where stopes are in close proximity. A major concern was the presence of open stopes (voids). In many cases, stopes consist of combinations of filled and void sections. The condition of pillars within these underground workings is extremely important. In time, pillars collapse and voids will propagate in upward and lateral directions. So systems needed to be developed that allowed rapid and accurate verification of ground conditions. KCGM was introduced to MDL Rock Lasers while investigating technology for underground mining. The two companies decided to use the C-ALS, MDL Rock Laser's underground laser, cavity scanning system, to improve the management of mining through affected ground. This system was to be used in conjunction with probe drilling and void mapping activities. A field test in one area of the Fimiston Mine verified the capability of the C-ALS system to quickly and efficiently assist in this decision making process. The C-ALS scanner features lightweight, carbon fi¬ber alignment rods from Measurement Devices Ltd.'s (MDL) Boretrak MKII. This is a borehole deviation system that stops the two axis measurement head rotating and lowers the system down a borehole. The scanner is deployed by a 110-mm (4.3-in.) borehole, up, down or sideways. The operator can then carry out vertical and horizontal plan section scans at any user specified ARC (an angular increment of 2°) or the distance between two points on the ARC (CHORD) increments. Windows '95 software enables the operator to control the cavity scanner remotely, surveying the area in real time. The system makes data quick and convenient.

Jan 1, 1999

By Richard W. Brummett

Problems in new strip mine development is a subject that could require several days to cover adequately. Coupled with the fertile imagination of television writers, we could probably expand it into a series rivaling Gunsmoke in longevity with just as many shootouts at sundown. It would-of course-be subject to a high Neilson Rating. To bring the subject into perspective, we will limit the comments to a general discussion covering western strip coal developments. Stimulated by increased demand for low sulfur coal, surface mineable western coal operations began a shift into high gear approximately four years ago. Then came last year's "energy crisis" that increased the pressure on coal development not only in the west, but nationwide. Several eastern power plants having dual oil and coal burning facilities were directed to discontinue using oil. Also, a number of new south and southwestern power plants scheduled to burn natural gas or of I commenced an ordered conversion to other fuels, namely, coal. The involved utilities with reserve positions accelerated their planning while others began the search for long-term commitments from coal producing companies. In addition, announcements were made for proposed mine mouth coal gasification projects in New Mexico, Wyoming, and North Dakota.

Jan 1, 1974

By G. Fehr, B. B. Panda, R. Bansberg, K. Arnold, T. Freiman

To evaluate the potential for process solutions to contaminate groundwater outside of the area of the Oxide Pit, it is necessary to predict the ultimate maximum pit lake elevation once pit-related mining activities have ceased. A water balance model was developed based on the existing pit geometry, the groundwater flow equation, and assumed hydrologic input parameters. The model assumed that at any point in time, total inflow into the system (i.e., direct precipitation, surface water and groundwater) minus outflow from the system (evaporation from the lake surface) was equal to the change in the pit water volume. The pit lake depth over time was predicted by assuming a succession of steady- state water balance conditions over short time increments. An analytical method using a spreadsheet and computer model was employed in this study to model the filling of the lake in the Oxide Pit. A sensitivity analysis was performed to evaluate uncertainty associated with the input parameters in the model. The sensitivity analysis indicated that the model was most sensitive to values of precipitation and evaporation and to the static water table.

Jan 1, 2003

By C. J. Hall

An investigation of multi-shaft airflow problems by the author in 1976 (1) was presented in the hope of arousing considerable written comment, but in fact-. only one contribution (2) was forthcoming. The investigation in this paper is taken several stages fur¬ther, because the matter is of major importance in many American hard rock mines with complex networks extending over thousands of meters vertically. The examples used have all been generated thermodynamical¬ly and checked by motive column (denisty) calculations. Dry air has been used to reduce the amount of time spent on the rather complex calculations, but it has been shown (3) that the principals developed apply equally well to air/vapor/water mixtures. Initially the subject is investigated using both thermodynamic and motive column analyses. The latter part of the paper concentrates on a motive column presentation. Both methods are, of course, equally valid and give identical answers to any situation when correctly applied, as is shown in the worked examples.

Jan 1, 1980

By Stanley J. LeFond

After two disappointing years where most industrial minerals posted decreasing production, 1981 saw an increase in production over 1980, or at least in status quo. Several commodities did, however, post significant gains. For example, bromine posted a 14% increase; fluorspar production dropped 21% in 1980, but gained 24% in 1981; and sulfur production increased. However, perlite was off 13% and manufactured sodium sulfate off 18% in 1981, while natural sodium sulfate production remained almost even with 1980. In fact, many industrial minerals production either remained constant, increased, or decreased only slightly over 1980. Increasing energy costs had their impact on industrial minerals in 1981. Hopefully, the recent downward trend in energy costs, at least gasoline, will financially help some of the more marginal plants. The 1979 shortage of rail cars that did not carry through 1980 also did not carry through in 1981. Rail rates increased 12.8% over-all last year, while average freight rates for industrial minerals increased 15.5%, according to Neil Johnson, consultant. Also, the trucking industry posted a 5-6% decrease in rates due to deregulation. All in all, we in the industrial minerals section seem to be holding our own at least. Stanley J. Lefond Contributing Editor

Jan 5, 1982

By Bern Klein, Richard W. Lawrence, Scott Frostad

A laboratory study was conducted to evaluate the effects of various kinetic test protocols on sulfate production, NP depletion and time to acidity. Six test protocols were evaluated including standard humidity cells, non-aerated cells, tall cells, shaken cells, simulated precipitation cells, and NP depletion columns. The study indicates that test protocols which disrupt the oxidizing environment, such as extreme wetting and drying cycles, shaking the cells, or the high addition of acidic water will create an unnatural environment that affect the results. Trickle leach and non-aerated test protocols create an oxidizing environment that more closely represents field conditions and are therefore recommended.

Jan 1, 2000

By Randal J. Barnes

There are many methods available for the estimation of geologic parameters (Popoff, 1966; Barnes, 1980). In the last decade a new and relatively sophisticated technique using statistical theory has emerged: geostatistical kriging (David, 1977; Journal and Huijbregts, 1978; Rendu, 1978). An interesting property of geostatistical estimation is that when a geologic parameter is estimated for a given volume, not only is the estimate generated but an associated measure of certainty is produced as well. This statistical measure of estimation confidence is called the estimation variance. While the concept of an estimation variance is universally considered to be a good idea, mining engineers and geologists do not currently have the tools to incorporate it into their planning and quantitative analysis. This paper attempts to develop and present some of the necessary tools required to incorporate estimation uncertainty into mine planning. Geologic uncertainty is portrayed as an economic business risk. This risk is objectively characterized, and-the associated cost is quantified. Geologic delineation sampling is viewed in this light as an economic commodity with an associated cost and value. A coal mine planning example is used as a focus in this presentation. The data used is real, though it has been modified to maintain data security and project anonymity.

Jan 1, 1986

By Jeffrey M. Christian

Gold prices are rising, in what is coming to be seen as the beginning of a longer term upward trend. After languishing between $325/oz and $364/ oz from early 1991 into early 1993, prices began rising in the first half of 1993. Gold rose from a low of $326/oz in March 1993 to $414/oz on an intraday basis in early August. There was a speculative sell-off at that point, which took gold prices quickly back down to $350/oz briefly in October 1993. At that time, there still was a fair degree of skepticism about gold's price prospects. Many banks believed that gold prices could not mount a sustained rally. As prices dropped in August and September of last year, these suspicions seemed to be confirmed. Gold prices quickly rebounded, however, reaching $395/oz by early January 1994. The strength of this renewed increase led many banks, investors and others that had held negative views of gold to grow more positive. They began buying gold and trading it from the long side of the market. The result was that gold prices remained strong during the first quarter of 1994, trading between $375/oz and $390/oz.

Jan 1, 1994

By J. Pinkley

In June of 2002 Hilti North America received the first MSHA permissible approval for usage of a powder actuated tool device in a gassy mine atmosphere. The purpose of this paper is to discuss the implementation of this commonly utilized tool technology in the construction industry, to the underground gassy mining industry over the course of the last 5 years. Prior to June of 2002, underground gassy mining industry had attached materials such as ventilation curtains, power cables, communication cables, signage, and other materials by either manually driving individual spads or nails into the mine roof or rib or by attachment to existing roof bolt bearing plates. The Hilti DX 460 powder actuated tool is portable, durable, and lightweight (4.5 pounds). The Hilti DX 460 powder actuated tool system is powered by Hilti .27 caliber permissible explosive boosters. The energy force of the Hilti .27 booster?s acts on a captive piston principle in the Hilti DX 460 powder actuated tool, that applies the setting force for the direct fastening to the individual fastener chosen for the application by the end user. Each year Hilti can be called upon by MSHA to provide booster materials for re-testing per our Hilti DX PAD 1/00 approval.

Jan 1, 2008