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By M. J. Hrebar

A study was conducted to evaluate the applicability of large wheel loaders (Cat 994 class) as primary loading equipment in open pit iron ore operations. Field visits were made to taconite and gold mines that used large wheel loaders. Data were gathered on loader selection rationale; operating and maintenance experience; and production, availability, and cost information. Brief time studies were conducted to indicate machine performance and utilization. The paper summarizes the field data and includes economic comparisons of wheel loaders versus cable shovels in an iron ore application.

Jan 1, 1996

By C. L. Karr

Researchers at the University of Alabama have developed a method for producing fuzzy linguistic models of mineral processing equipment directly from engineering data. These fuzzy linguistic models rely exclusively on data collected from the processing systems being modeled and do not presuppose an understanding of the physics of the system. The fuzzy linguistic models use descriptive rules and explicit membership functions that provide a precise, nonmathematical description of the processing equipment. A genetic algorithm is employed to simultaneously select rules and tune membership functions used in the fuzzy models. The result is an extremely flexible approach to modelling that is applicable in a variety of linear and nonlinear systems. The effectiveness of this approach to modelling is demonstrated using a four-input, two-output model of a grinding circuit.

Jan 1, 1996

By H. J. Zhang, W. Wui

With the adoption of market-oriented economic policies, Chinese non-ferrous metals industry has gained remarkable progress. The continuously increasing domestic demand for non-ferrous metals, however, calls for more import of raw materials in short supply, such as copper concentrate and bauxite. As an alternative for balancing the shortage and assurance of more stable mineral supply, direct investment in oversea mining project has come to the agenda. This paper discusses the computer-assisted method used for evaluation and comparison of potential mining projects.

Jan 1, 1996

By L. H. Michaud

A mining company plans to extend its surface coal-mining operations in central Pennsylvania. Although the proposed site contains pyritic material, the results of the acid-base accountings for the site shows an overall Neutralization Potential to Maximum Potential Acidity Ratio (NP:MPA) of 4.26:1 for the entire site. The pyritic material is, however, associated with the lower of the three seams to be mined. If traditional dragline-mining methods are used, this would result in the acidic material being placed at the top of the spoil piles, exposing it to air and water, and therefore to the formation of acid mine drainage (AMD). Further concerns are associated with the fact that the alkaline material is not distributed evenly over the mine site. To prevent the formation of AMD, the company has proposed to mine the area using truck-shovel mining methods. This technique offers a more flexible alternative for cut sequencing and for the selective placement of waste material. Working with the Department of Mineral Engineering at The Pennsylvania State University, amine plan was developed for this site. This plan results in the layering of the alkaline and acidic spoil to achieve an overall net alkalinity in all spoil areas. Therefore, mining this site should not result in the formation of AMD.

Jan 1, 1996

By G. A. Doyle

The quality of water in mine pit lakes depends in part on the physical limnology (Le. stratification, turnover, and development of anoxic conditions with depth) of the lake. Limnologic data collected from four existing pit lakes indicate that pit lakes develop a thermocline, or temperature stratification, in the upper 10m to 30 m of the water column. Two of the pit lakes (26 m and 55 m deep) undergo seasonal turnover of the entire water column, whereas two deeper pit lakes (110 m and 240 m) undergo seasonal turnover of only the upper portion of the water column. In the deeper lakes, seasonal mixing does not extend through the entire water column and a distinct chemocline develops with depth.

Jan 1, 1996

By William J. Miles

Bentonite Corporation decided to pursue ISO-9002 Registration for our bentonite production for many reasons. We wanted to improve our current Quality System to encompass all business aspects, not just Quality Assurance. We wanted this system to build supplier/customer confidence and provide our customers with all the services that they needed for their business functions: such as Quality Assurance for their needs; appropriate shipping and delivery; appropriate billing; and appropriate sales, technical and management support of our product. These objectives of our Quality System are addressed by the ISO 9000 clauses and requirements. There were additional reasons and expectations for implementing an ISO 9000 Quality System. ISO 9000 registration would develop and aid international sales since the ISO system is a basic requirement in many parts of the world such as Europe and the Far East. It would bring acceptance of bentonite products by new customers and markets Another objective was to develop better trained employees. We hoped that the ISO Quality System would help us reduce costly non-conformances and reduce overall production and operating costs. We hoped to achieve ISO 900 registration before our major customers required it. For example, our major market is use of bentonite as a binder in foundry mold sand systems. The foundries in North America primarily service the automobile manufacturers who have individual Quality System requirements that are being merged with ISO 9000 Standards. As the foundries addressed the automobile manufacturer?s needs, Bentonite Corporation received numerous inquiries and surveys of our Quality System and its conformance with ISO 9000 Standards. Eventually, ISO 9000 Registration will become a requirement to directly or indirectly service this market.

Jan 1, 1996

By Evangelos Spyridonos, Thomas Frommer, Wolfdietrich Skala, René Prissang

Operational grade modelling is a technique that uses production data to run daily updates of property models. It will enable mining engineers to use property predictions based on the most recently acquired data as support for quality control and decision making. The approach necessitates that the properties of the run- of-mine material can always be attributed to individual mining blocks or charges. The software employed must be highly reliable, because a system failure or the loss of data could seriously affect the mine's quality management. An operational grade modelling system has been developed for the Breitenau magnesite mine. It makes use of the Linear Octree Based Property Modelling system which was conceived and realised at the Free University of Berlin. This paper describes the system design and gives an account of the experiences during the first six months since system start-up.

Jan 1, 1996

By Jr. Matthews

The Candelaria copper-gold deposit is located in Region m of Chile, 805 kilometers north of the capital, Santiago. Candelaria was discovered in 1987, following a six month exploration program. In late 1986, induced polarization (IP) surveys outlined an anomalously high response within the area of interest. The first test hole bad three intersections totaling 49 meters, with an average grade of 1.97% copper. Drilling eventually outlined approximately 390 million tonnes, grading 1.09010 copper and 0.26 grams/tonne gold. Production began in early 1995 and is estimated at 120,000 tonnes copper and 80,000 ounces gold annually.

Jan 1, 1996

By N. B. Prenn

Case Studies in Open Pit Design Using Whittle 4D will be discussing the following four examples: 1) Optimization of process plant design using Whittle 4D as a sizing tool. In this case, the home office and project team had different views of the size of the final project. The home office wanted to reduce the size of the project to reduce capital expenditure, while the project team suggested a larger project. Whittle 4D was used to determine Net Present Value and Internal Rate of Return using the Whittle scheduler (FDAN) to schedule many alternatives, and calculate the NPV and return for each alternative. 2) Comparison of pit optimization methods: Lerchs-Grossman vs floating cone. Many pits are developed based on floating cone economics. A comparison of methods in one large gold mine resulted in the stripping ratio of the pit being reduced by 10% in the Whittle 4D optimization as compared to the floating cone optimization. 3) Pit optimization to determine if a new mill is justified. A large heap leach gold and silver mine needed to determine if a new mill was justified. The planning and scheduling would take several man months if completed without pit optimization and scheduling software. Whittle 4D software proved to be very effective in providing optimized pits and a mine schedule in a short time frame. 4) Pit optimization to determine how to mine and size. Open pit optimization determined where the underground operation should start, and whether the material should be processed by milling or heap leaching. One of our clients asked for help in determining where the pit should end and a new underground operation start. We used Whittle 4D to help determine where the pit should end and where to go underground. In addition the operation needed to determine how to process the material.

Jan 1, 1996

By J. W. Leonard

Comments The venerable straight-line equation Y = Bx + A is again being rediscovered, but this time by economists, mining engineers and geologists. Two economists, William Sharpe and Harry Markowitz, from the University of Chicago and Stanford University, respectively, won the 1990 Noble Prize in economics by showing that the price of individual stocks can be related to the Dow Jones industrial average (DJIA) using the straight-line equation. According to Bill Chidester, Investment Analyst, Scientific Investment, Sharpe and Markowitz strongly emphasized the role of the beta (B) value while considering the alpha (A) value to be "pretty unimportant." Chidester claims that alpha is the "mystery" value that causes individual stocks to behave independently of popular stock-market indices, such as the DJIA. For many years, mining engineers and geologists have routinely called alpha the "nugget" or surprise element in geostatistical analyses in which a designated distance (x-axis) is related to the variance of the grade (y-axis). Because the influence of the independent variable (distance) over the dependent variable (grade variance) is ideal when alpha is equal to zero, any increase in alpha represents a loosening of influence or control within the relationship. This can be good news or bad news - good news if you are an economist sorting out off-trend stocks and bad news if you are a mining engineer trying to predict sulfur in a coal seam. With many mining trends, such as those involving the relationship of distance to the variance of grade, a mathematical relationship can be formed. In geostatistical analysis, the point where a mathematical trend ends is known as the sill. If the difference between the variance of grade at the sill and at alpha can be determined, then an estimate of the relative control for a given distance can be obtained by comparing the sill value to alpha. The extent to which alpha approaches the value of the sill provides an indication of independence or loss of trend. The alpha concept may find application with distance, time or fluid problems. The point of change can be either a change in trend or the trend limit. However, even without a clearly defined point of change or trend limit, increasing alpha values always infer loss of trend. Alpha analysis should be regarded as a valuable tool when sorting out many sets of mining data. The application of this user-friendly concept to reserves, material transport, fluid flow and other areas has been, and will continue to be, the basis of many important past and future developments in mining and geology.

Jan 1, 1996

By K. H. McDaniel

An interactive mine ventilation simulation software program (WIPPVENT) was developed at the Waste Isolation Pilot Plant (WIPP). The WIPP is a U.S. Department of Energy (DOE) research and development project located near Carlsbad, New Mexico. The facility is designed to provide a permanent, safe underground disposal of U.S. defense generated transuranic waste in bedded salt. In addition to its regular functions, the underground ventilation system is engineered to prevent the uncontrolled spread of radioactive materials in the unlikely event of a release. To enhance the operability system, Westinghouse Electric Corporation has developed an interactive mine ventilation simulation software program (WIPPVENT). While WIPPVENT includes most of the functions of the commercially available simulation program VNETPC (copyright © 1991 Mine Ventilation Services, Inc.), the user interface has been completely rewritten as a Windows ® application and screen graphics have been added. WIPPVENT is designed to interact with the WIPP ventilation monitoring systems through the site wide Central Monitoring System.

Jan 1, 1996

By H. R. Thompson

The Grant Town Power Plant is a nominal 80 MW (net) Waste Coal-Fired Electric Generating Plant which is located in northern West Virginia, approximately 15 miles southwest of Morgantown. The Steam Generator consists of two (2) Pyro-Power Circulating Fluidized-Bed Boilers (CFB), each rated at 400 000 lbs/hour @ 1,350 psig. Main Steam. The Turbine Generator is a single GEC Ahlstrom unit rated at 95 MW gross and 80 MW net. The Plant began commercial generation during April, 1993. The facility is owned by American Bituminous Power Partners, L.P. (AmBit), and operated by Mission Operations and Maintenance, Inc.

Jan 1, 1996

By L. A. Puchkov, Mesentsev. V. K., I. O. Temkin

The problem of increasing underground mine ventilation efficiency is still of top priority. The complication of geological conditions with the depth of underground mining processes and reinforcement of requirements to technological and ecological safety are extorting the necessity of solving this complex problem with using of new information technologies. There exist different approaches to the ventilation problem. One of them, which the authors adhere to, is based on the concept of monitoring (under special mining and geological conditions-automatic control) of mining atmosphere and operative re-distribution of underground mining air among consumer , in accordance with the criterion of optimality [ 1.3 1. ] The set of tasks which should be decided in the frame of con- crete ventilation system depends on the peculiarities of deposit, technological schemes and so on. Nevertheless, some ventilation tasks such as: defining of ventilation network parameters; finding of dependence between these parametrs; operative redistribution of air streems, could be interpreted as universal ones. Main aspects of practical solving of different ventilation problems and their classification were investigated and considered in detail before [I ,2 ]. Some years ago we have began our investigations to develope quite simple and effective methods for decision of ventilation tasks on the base of neural network technology. It is well known that ventilation net, formed by various mine workings, is the main component of underground mining ventilation system. In general, network air distribution may be described by some functional F(Q,R,H), where Q- is a vector of air consumptions; H- is a vector of depressions; R- is a vector of airdynamic resistences. (Q,R,H) - are the informative entities , characterising every branch of the net. There exist some fundamental tasks which should be decided during the process of control of mining ventilation: calculating of natural air distribution Q = Q,{R, H,}, or Q = Q2(R, Q?}, where H, - is the maximal depression of the ventilation net, Q, - is the air consumption in the ventilation shaft; identifying of airdynamic resistance for some branches on the base either of air-depression removal or operative monitoring: [ ]

Jan 1, 1996

By E. V. Kuzmin

The rock properties improvement means the exchange of natural properties: increase of stability, strain and compress tension, reduction of gas-liquid filtering property, increase Jung- module, other mechanical and physical parameters of rocks by injection the hardening materials, such as polymeric pitches, micro-or geocements by special technology under high pressure, to fill cracks. Flow of liquid materials between the rock units and hardening under high pressure create full redistribution of rock pressure in rock massif. There are many reasons to use this technology in underground mining, tunnelling, creation barrier technology in raioactive, chemical and other danger material site etc.

Jan 1, 1996

Because the Environmental Protection Agency has identified methane as a greenhouse gas, the importance of de gasification through gob wells has become more critical. It has been observed that the degree of methane emission is closely related to the geomechanical characteristics of coal bearing strata, roof, floor, and surrounding coal seams. Monthly production data from 250 gob wells were collected from the Warrior Basin in Alabama, and many interesting correlations were observed between methane production with longwall face width, face advancement rate, number of gob wells in a panel, and geologic columns. Extensive finite element analyses were performed to estimate the characteristics of the emission zone in an attempt to corroborate these findings. This paper describes an investigation for developing correlations between the geomechanical behavior of the methane emission zone with methane production.

Jan 1, 1996

By H. Sevim

Three transportation and handling alternatives for delivering dry coal combustion residues from power plants to underground coal mines were evaluated technically and economically. The objective was to transport, handle, and inject the residues into the old workings of the mine at a minimum cost. This objective was accomplished in two steps: I) Simulation models were developed and utilized in identifying technically feasible designs in each alternative, 2) Technically feasible designs were economically evaluated to obtain the cost-per-ton of material transported. The designs that provided the minimum cost-per-ton were declared optimal An analysis was conducted for varying distances and tonnages to reveal favorable operating ranges of each alternative.

Jan 1, 1996

By J. G. Groppo

The Andritz Ruthner Inc. hyperbaric filter was evaluated at a pilot scale for dewatering fine coal cleaned by froth flotation. The pilot scale dewatering testing was conducted at a solid feed rate ranging from 100 lbs to 200 lbs/hr-ft2. Effect of hyperbaric operating parameters and addition of various surfactants and flocculants were evaluated on dewatering of fine coal. The tests data indicated that for the minus 100 mesh and minus 28 mesh clean coal product, the Andritz hyperbaric unit provided filter cake containing 23 percent and 14 percent moisture, respectively.

Jan 1, 1996

By D. D. Harbuck, G. K. Green

The Bokan Mountain area on Prince of Wales Island, AK, contains vast quantities of heavy rare earth minerals. To lessen the US dependence on foreign sources, the US Bureau of Mines (USBM) investigated yttrium recovery from this ore. By sulfating the ore at 250 ° C for 1 hr at an H2S04:ore ratio of 1:1 and then water leaching the sulfated material for 1 hr at 20% solids and 25ºC, over 74% of the yttrium, cerium, and lanthanum were solubilized. Solvent extraction (SX), using a synergistic combination of OPAP and DEHPA, selectively loaded 100% of the yttrium. Yttrium was stripped directly as a solid using a 2M, 35 ° C NaOH liquor. When the OPAP/DEHPA mixture was tested in a continuous SX circuit, yttrium loading and stripping were 100% and 96%, respectively. The organic showed excellent recyclability properties with minimal solvent loss.

Jan 1, 1996

By Peter K. Achireko, Samuel Frimpong

Design and optimization of open pit limits are of paramount importance because they provide information for evaluating the economic potential of a mineral deposit and for developing short and long range mine plans. Many algorithms and their modifications have been used to design and optimize open pit limits. These algorithms have provided mine planning engineers with pertinent information in designing, optimizing and extracting ore reserves by open pit technology. However, they do not address the random field properties associated with the ore grades and reserves and commodity prices, and thus, fail to yield the truly optimized pit limits in any time horizon. In this paper, a new algorithm, MCSIMFNN, which overcomes these limitations is proposed and used to optimize open pit limits. The random field properties of the ore grade and reserves have been modelled using the modified conditional simulation based on the best linear unbiased estimation and local average subdivision techniques. Artificial neural networks are used to classify the blocks into classes based on their conditioned values. The error back propagation algorithm, in the neural networks, is used to optimize the pit limits by minimizing the desired and actual outputs error in a multi- layer perceptron under the pit wall slope constraints. The optimized pit value obtained by this algorithm has been compared to that from the Lerchs-Grossman's algorithm in a case study. The results are the same, but in random multivariable states, the MCSI MFNN algorithm is the most suitable for pit optimization. The method is also fast since it mimics the operation of the brain in the solution of the pit optimization problem.

Jan 1, 1996

The National Mining Association’s (NMA)MINExpo International ’96 is shaping up to be the organization’s largest. About 30,000 mining industry business and technical professionals are expected to descend on Las Vegas, NV Sept. 9-12 to take part in the 25 technical sessions and visit the more than 900 exhibitors who will be showing off their products and services. MINExpo will be the largest mining equipment and services exposition in the United States this year. Exhibits at MINExpo will fill the Las Vegas Convention Center, parking lots and part of the Hilton Center, located next door to the convention center. NMA estimates that this year’s show will cover more than 46,450m2 (500,000 sq ft) of exhibit space. Some of the exhibits on display will include haultrucks, hydraulic shovels and excavators, conveyors, continuous miners and tunneling machines. In addition, an array of computer equipment and software will be demonstrated. A new feature this year will be a helicopter pavilion, located in the Hilton Center. Helicopters and fixed-wing aircraft have become indispensable to many remote mining operations. NMA said that at least one full-size helicopter will be on display.

Jan 1, 1996