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By A. Pradakar, J. G. Groppo, J. W. Leonard

All coal transportation systems from the coal face to the final point of use would become more productive if additional tonnages, obtained through improvements to bulk density, could be placed in fixed volume containers such as scoops, shuttle cards, trucks, barges and ships, as well as conveyors. This paper reviews previously reported work where the treatment of coals with small amounts of mining chemicals (0.12 to 0.28 kg/t or 0.25 to 0.56 lbs/st) during lavoratory testing was show to increase loaded coal bulk density by about 15%. The latest bulk density enhancement findings to develop from ongoing research involving underlying chemical and physical theory together with the added use of simple mechanical excitation are discussed.

Jan 1, 1995

By S. Nickson, M. Grenon

Oriented borehole data provide the means to characterize a rock mass. In this paper, the geomechanical caving potential of a hard rock mine project is investigated. In particular, the influence of random joints to the resulting block size distributions is addressed. The implications of this approach in preliminary investigations on the choice of mining methods are discussed with reference to one site.

Jan 1, 2003

By P. Grotjohann

In processing heavy mineral sands, the low feed concentration and respective high value of the desired minerals require high capacity production and sharp classification/separation techniques to reduce the specific production costs. The allflux® separator, a new process system introduced to the heavy mineral industry, meets these criteria in an economical way. Its two-stage process, a combination of rising current and fluidized bed technology, allows the treatment of extremely high massflows in a single unit. Using concepts that have proven successful in processing concrete sands for many years, testwork in coal, iron ore, and heavy minerals looks very promising.

Jan 1, 1998

By D. M. Conner

An innovative patented process has been developed to convert high volume wastes--fly ash from coal-fired power plants, municipal solid waste (MSW) ash from incineration, solids from waste water treatment and paper mill sludge into a high value and environmentally benign product in the form of a lightweight aggregate. Lightweight Aggregate is widely used in the building construction industry in the United States, Europe and some Asian countries. This paper will present the development of the process, the process itself and details on the first commercial scale plant. The commercial plant is owned and operated by Wisconsin Electric Power (WEPCO).

Jan 1, 1997

By W. R. Dearman, N. Turk

The theoretical relations between the strain and stress Mohr circles make it possible to establish a relation between the internal friction angle [ ] and the Poisson's ratio (v) of rocks. The internal friction angle is related to the Poisson's ratio as Sin [-] = (1 - v)/(l + v). This relation gives lower friction angle values than the triaxial Mohr envelopes and higher values than those given by surface sliding friction tests.

Jan 1, 1986

By Ellis G. Goree, George A. Simmons, Andrew B. Pervis

The pneumatic classifiers are widely used for fine dry powders separation These classifiers can be used for either the removal of fines from coarse feeds or the removal of coarse particles from ultrafine feed To optimize the operation of pneumatic classifiers, a thorough understanding of the impact of operational parameters on the efficiency of classification is essential This paper describes the design features and effects of operational parameters followed by illustrations of pneumatic classifiers usage in two case studies

Jan 1, 1983

By John D. Gardner

This paper describes a process which finds the maximum worth of a mineral deposit. The procedure requires two phases. The first uses a microcomputer evaluation model to find the optimum design input, with minimum attention giving to actual mining constraints that might exist. The second phase runs the first-phase design parameters through a direct simulation model on a mainframe computer. In phase one, financial, economic, and geotechnical data are entered; and an idealized list of design parameters is output. The list includes optimum values for cutoff grade, mine life, mine size, paytons, paygrade, and payvalue. In addition, the model generates pro forma operating and cash flow statements and it indicates the maximum net present value (NPV) possible for the deposit along with the probability of that oc¬curring. The initial results imply perfect mining conditions. In phase two, when actual mining selectivity, sequence, and other practical design considerations are related in a direct simulation model to the optimum criteria found above, the maximum NPV invariably decreases. However, if it is still satisfactory (NPV greater than or equal to zero) then the maximum worth/ optimum design have probably been found in the first iteration. If, on the other hand, NPV is now unsatisfactory, then design compromises must be made and simulated, and the results rerun through the evaluation model. If several iterations fail to yield a positive NPV then the deposit is most likely unfeasible t for the forecast economic conditions used in phase one.

Jan 1, 1986

By G. Mbuyi Kamba

Literature is rather abundant on the topic of steady-state network analysis programs. Many versions exist, some of them have real extended facilities such as full graphical manipulation, fire simulation in motion, etc. These programs are certainly of great help to any ventilation planning and often assist the ventilation engineer in his operational decision making. However, what ever the efficiency of the calculation algorithms might be, their weak point still is the overall validity of the model. This numerical model, apart from maybe the questionable application of some physical laws, depends directly on the quality of the data used to identify its most influencing parameters such as the passive (resistance) or active (fan) characteristic of each of the branches in the network. Considering the non-linear character of the problem and the great number of variables involved, finding the closest numerical model of a real mine ventilation network is without any doubt a very difficult problem. This problem, often referred to as the parameter adjustment problem, is in almost every practical case solved on an experimental and "feeling" basis. Only a few papers put forward a mathematical solution based on a least square approach as the best fit criterion. The aim of this paper is to examine the possibility to apply the well-known simplex method to this problem. The performance of this method and its capability to reach the global optimum which corresponds to the best fit is discussed and compared to that of other methods.

Jan 1, 1995

By J. W. Hawkins

Understanding aquifer properties in surface mine backfill is essential for managing the groundwater flow system as well as controlling the formation and discharge of acid urine drainage. Slug tests (injection and withdrawal) performed on wells in mine spoil may yield two distinctly different response characteristics. One type of response is indicative of a porous media system. The second type of response indicates the presence of a pseudokarst system. The presence of voids or conduits in the backfill is indicated by an almost instantaneous partial recovery of the water level displacement. This rapid recovery is turbulent flow and cannot be analyzed by conventional (Darcian) methods. The turbulent flow may cause the calculated hydraulic conductivity to be less than the actual values. The slug dissipation surface area created by the voids contiguous to the test well add to the known dissipation surface area of the screened interval. This can cause the calculated hydraulic conductivity to be greater than the actual hydraulic conductivity or the aquifer to appear more permeable. Whenever analyzing data from aquifer tests in mine spoil, these potential problems must be kept in mind. In spite of the problems encountered during slug testing of spoil, the aquifer hydraulic parameters derived and the slug responses observed remain useful in the hydrologic characterization of a mine site.

Jan 1, 1994

By Gary L. Simmons

Over the past several years, Newmont Gold Company (previously Santa Fe Pacific Gold Corporation) developed a new technology for the flotation of refractory auriferous sulfide minerals which is referred to as the N2TEC flotation process. Starting in April 1997, the first commercial flotation plant utilizing N2TEC technology was successfully commissioned at the Lone Tree Mine near Valmy, Nevada. The Lone Tree flotation plant was designed to process 4,085 mt/d of ore producing 494 mt/d of sulfide concentrate. A flotation tails leach CIP circuit was added to recover cyanide-soluble gold from the flotation tails. A portion of the flotation concentrate is blended with whole ore feed to the Lone Tree autoclave, up to the limit imposed by the current oxygen plant capacity. The remainder of the concentrate is shipped to either the Twin Creeks autoclaves or the Carlin roaster for subsequent oxidation and gold extraction. This paper discusses the results achieved in the commercial flotation plant compared to pilot plant testing and engineering design flotation modeling. Capital and operating cost information are also presented.

Jan 1, 1999

By William E. Hole

The sand and gravel industry provides an enormous quantity of materials vital to the maintenance of low-cost construction. There has been little effort to conserve this valuable natural resource. In fact, existing regulations which affect sand and gravel operations act more to waste these materials than to conserve them. Another factor affecting the industry is new legislation requiring the reclamation of worked-out pits. Although such legislation creates many administrative headaches for a sand and gravel operator, there exists the possibility through such legislation of gaining some conservation measures that could be helpful to the industry.

Jan 1, 1974

By T. A. Toney, L. R. Fish, P. J. Bethell

With new lightweight designs, spirals have become standard equipment in coal preparation plants worldwide. To their credit, spirals typically show very low coal losses to the refuse stream under most operating conditions. However, spirals do tend to separate at cut points in excess of 1.80 S.G. Attempts to obtain lower cut points have typically resulted in coal losses to middlings. Middlings retreatment with secondary spirals is therefore becoming common place. Other forms of retreatment with water-only cyclones, hydrosizers and recirculation have been attempted with some success. This paper reports on a novel (patent applied for) approach to retreating spiral middlings in a heavymedia cyclone circuit.

Jan 1, 2000

By D. Kump

Barrick closed the Bullfrog Operation in November 1999.During its life, the Bullfrog produced ore from three open pit mines and an underground mine; 32,000,000 tons of ore were processed at the 9,000-ton per day oxide mill. The mill tailings were deposited in a 320-acre tailings impoundment. When operations ceased, an estimated 750,000,000 gallons of water remained to be removed from the tailings impoundment. During operation, the drain down water from the tailings impoundment was pumped back to the mill for reuse; since closure of the mill, the drain down water has been managed by a combination of passive and forced evaporation.

Jan 1, 2004

By S. K. Kawatra, T. C. Eisele

In many mining operations, particularly northern open-pit mines, large seasonal variations in grinding slurry temperature can occur. It is shown in this paper that this temperature shift can cause a winter-time loss in autogenous grinding efficiency of as much as 20% if it is not controlled. Laboratory experimentation indicates that much of this effect is due to increases in slurry viscosity as the temperature is decreased. An additional effect may result from changes in rock strength upon freezing, for which possible mechanisms are discussed. However, no effect clearly resulting from rock strength changes has been definitely confirmed.

Jan 1, 1992

By K. L. Kasperski, M. T. Ityokumbul

The effect of reaction conditions on the desulfurization of oil-sand coke residues was studied. The variables investigated were temperature, reaction time, heat transfer resistance and mode of caustic soda addition. The results show that oil-sand coke desulfurization increases with temperature, reaction time and heat-transfer rate. In an oxidative environment, coke combustion during molten-caustic leaching (MCL) commences at temperatures above 500 °C. The mode of caustic addition has no effect on coke desulfurization.

Jan 1, 1996

By Venkata S. Vutukuri

Assuming a number of discrete leakage paths and treating the airflow through leaky duct line as a series-parallel combination of airflows along the duct and through leakage paths, exact solutions for auxiliary ventilation problems can be obtained. A computer program "SEGMENT'' has been written to solve problems using this method. However, most of the investigators have treated the duct lines with a uniformly distributed leakage and many have derived formulas assuming various boundary conditions and levels of simplification for the design of a simple auxiliary ventilation system An appraisal of accuracy of the various formulas has been conducted using the results from the program "SEGMENT' as benchmark and the formulas which give accurate results have been identified. The ranges of application for all the formulas have also been determined for 5 %error.

Jan 1, 1993

By Fang-tu Wei

The purpose of developing this system is to monitor the operating status of the fully mechanized mining system in order to raise it's reliability. The completely mechanized coal mining system is a complex dynamic system, involving many sub-systems. It is the key of the mining process as well as a connected system composed of each working procedure. Any hitch in breaking, loading or transporting will interrupt the mining process. The analyses of the operating data has proved that the reasons causing the interruption of the extracting processes mainly come from the inner of coal face. Hence, after the installation of the MINOS system in England, the delays of belt conveyor sub-system were reduced. But the production increment was not as much as expected.

Jan 1, 1986

By René E. Fuenzalida

The copper market has become highly competitive around the world; therefore, operations efficiency is a must for copper producers. The economic outcome in a day-to-day milling is not evident at the concentrator stage, when traditional procedures are used in operations management, based on the supervision of process variables and metallurgical indices. Therefore, in such a complex business, there is a strong need to devise an approach to furnish concentrator's operators with procedures and tools to state and solve the problems related to operational decision making, leading to maximize the economic return of investment; this is what is aimed to be presented in this paper.

Jan 1, 1998

By Michael L. Nave

Mining belt conveyor elements are becoming larger and more expensive. Conveyor reliability requirements are rising. Conveyor condition monitoring can aid maintenance, reliability, and risk management in conveyor system operation. This paper examines the application of condition monitoring in coal mining belt conveyor systems. Types and form factors of condition sensors are described. Example costs are included. Suggestions for OEM developments are examined. Application problems are discussed. Two simple cost case studies are presented.

Jan 1, 2000

By Maxine Wiber, Ross D. Gallinger, Brain A. Lewis

Poirier was an underground copper and zinc mine located in Northern Quebec that operated between 1965 and 1975. There are 5 million tonnes of acid-generating tailings, which have contributed acidity and metals to the Kananewesig and Kistabiche Creeks. The final closure plan incorporates the placement of all reactive material into the tails basin, installation of a geomembrane liner over the tailings deposit and a one metre soil layer to protect the liner. The environmental effect of the residual seepage was assessed from an ecological risk perspective. The Reclamation Plan has been accepted, and work commenced in 1998 to restore the site.

Jan 1, 2000