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By J. P. Savely

This paper describes the development of a trim blast design to improve the stability of a final pit wall. Description is given of the effects of rock characteristics, rock type, and pit plans on the blast design. Currently, six benches have been mined with trim blasting. A more stable final wall has resulted and the successful program has reduced mining costs over an extended time period. Low-cost blast monitoring and field observation were used to determine peak particle velocity and blast damage. Using criteria developed from this relationship, trim blasts were designed and evaluated.

Jan 1, 1987

By G. Raspa

This article describes a procedure for calculating the recoverable reserves of stratified orebodies characterised by a thin and irregular layers. An application on the phosphate deposits in the N'Zeto region of the Popular Republic of Angola is also described. The procedure consists in building a block model of the deposit through the conditioned multivarial geostatistical simulation of small areal units. The recoverable reserves are then calculated and defined by applying to the model a selection processes based on measured geological/economic parameters taken from the drillholes: thickness of overburden and mineralised layers, economic grain-size fraction, grade. The procedure also takes account both of the geometrical constraints of the mining method and dilution. For reasons of confidentiality, a multiplier has been applied to the values adopted for the sampling data.

Jan 1, 1992

By Henry P. Cole, Andrzej M. Wala

Engineers and psychologists at the University of Kentucky have developed simulation exercises that teach and test proficiency of mining technical personnel for coping with planned and accidental connections between separate air courses in underground mines. The exercises are based upon investigations of actual mine disasters. The exercises are judged as valuable and interesting training materials by experienced mining personnel. Although these specialists generally perform well on the exercises, potentially fatal errors are not uncommon. The use of such realistic exercises may better prepare miners for preventing and coping with underground mine ventilation emergencies.

Jan 1, 1987

By Robert J. Wise, Mark Alspaugh

Underground longwall coal mines depend on conveyor haulage to transport large volumes of coal from the longwall face conveyor to the mine portal. In the last few years, the need for longer and larger longwall panel conveyors has become very significant. In order to keep conveyor equipment to a minimum and still transport higher tonnages over longer lengths, intermediate drive technology has been developed. The use of DC motors and controls in conjunction with load sharing techniques have a1 so proven effective. A case study of a new longwall panel conveyor at Utah Fuel's Skyline Mine incorporating these design techniques will be presented.

Jan 1, 1993

By M. Karmis

The algorithms for the mathematical modeling to predict productivity of underground room-and-pillar mining systems are well known and documented. These algorithms consider the time-varying relationships between mining equipment for a given geometty of operations as well as other constraints. This paper presents WebConSim, a newly developed, Web-based, user-friendly computer simulation tool for the Windows environment. The simulator is easily customized for use by field engineers, planning engineers and management and will help mine operators plan the optimum mining sequence for different mine geometrie and equipment layouts. Program output includes production data and equipment utilization indices, as well as time driven event chains that can be used for virtual reality presentations.

Jan 1, 2002

By James Lonergan

This paper describes the application of the Graphics Assisted Under Ground Engineering (GAUGE) software to a 2-layered room and pillar hard rock mine. The graphics- assisted mine modeling and mine planning capabilities of GAUGE are demonstrated. The system uses polygons to model the room and pillar mine design and displays the model in plan view on the graphics screen,. The planning engineer interactively specifies areas to be mined in the medium or long term. The system calculates and accumulates tonnages and grades for the user-specified areas based on the layer being mined and the particular unit operation (drifting, widening or benching).

Jan 1, 1989

By Z. T. Bieniawski, Christopher Mark

A new method for the design of long- wall chain pillars, called Analysis of Longwall Pillar Stability (ALPS), is described. The method provides estimates of the relative stability of different longwall pillar designs during all stages of their service life. The key issue addressed by ALPS is the magnitude and time-of-arrival of the longwall abutment loads applied to chain pillars. A field study was conducted and other available field data were analyzed in order to develop an approach for estimating the abutment loads. An example based on longwall experience in the Pittsburgh seam is used to illustrate how ALPS can be used in mine design.

Jan 1, 1986

By Jan Walaszczyk

The paper concerns the calculation of stresses and displacements in working area of room-and-pillar mining system of cooper ore mines. A three-dimensional rock mass model based on the finite element method has been developed. The complete strain-stress characteristic for pillars has been applied, but for the purpose of modeling the curve has been approximated by three segments of lines: - the first represents a behavior of pillar before a failure, -the second corresponds to a progressive pillar failure phase, - the third represents the part of the curve, where the increase of strains do not cause the stress changes, and it is called the residual strength. The criterion of model stability has been derived, which can be useful for predicting rockmass stability. The programs have been built, which allow to calculate stresses in bar elements, displacements in plate nodes, and estimate the stability of the model, which consists of plate elements and one-dimensional elements with a segment strain-stress characteristic. The programs were used to consider two different problems, which are connected with mining design and the exploitation systems.

Jan 1, 1992

By Kathleen S. Smith, Katherine Walton-Day, James F. Ranville

Four different scales of observation were used to evaluate the potential effects of a fluvial tailings deposit on water quality along the flood plain of the upper Arkansas River south of Leadville, Colorado. First, we collected surficial material and subjected it to batch water-leaching test. Second, we excavated and leached an intact eight-inch diameter core. Third, we examined the water quality of the shallow ground water beneath the fluvial tailings deposit, and fourth, we monitored water quality along a 5-km reach of the adjacent Arkansas River. Leaching of surficial samples indicates that there is a reservoir of readily water-soluble material yielding elevated metal concentrations and high acidity. However, there are minimal measurable water quality effects of the fluvial tailings deposit on the adjacent reach of the Arkansas River.

Jan 1, 2000

By F. F. Aplan

Estimations have been made of the tonnage of raw ores and coal treated by various beneficiation processes. The amount treated by gravity concentration is substantially greater than that treated by flotation, with coal representing the bulk of the material treated by gravity means. A discussion is given of the trends and anticipated improvements in gravity methods. Except for the concentration of iron ores, magnetic and elec- trostatic separation processes find their greatest use in the beneficiation of non-sulfide ores. Exciting new developments in magnetic materials and separation process (and, to a lesser extent, in the electrostatic process) indicate a substantial increase in the application of such processes to ores and a broad variety of non-ore uses.

Jan 1, 1989

By Robert J. Watters, Peter C. Kelsall, Joseph G. Franzone

Two separate studies investigated the compressive strength of basic igneous rocks and its relation to index properties such as porosity, density and soundrave velocity. The rocks tested were weathered dolerite from S. W. England and vesicular lavas from California. In both cases strength was affected considerably by porosity. In the dolerite, strength was also affected by fissures (microcracks) which were formed in the parent rock by shearing and later accentuated by weathering. While test results show that porosity, density and sound velocity are not reliable indices of rock strength, these properties are useful in interpretation of strength test results. Index testing can be used to classify samples according to similar behavior and to recognize the influence of fissures.

Jan 1, 1986

By Robert W. Bartlett

Pretreatment of sulfidic refractory gold ore by biooxidation in coarse-crushed ore heaps is a promising new technology, especially for low-grade ores that cannot afford pressure leaching or roasting. An algebraic equation for determining the economically optimum biooxidation of the sulfide minerals in the ore is provided that is based on the empirical biooxidation rate constant for the ore, the project's financial discount rate, the ore grades of both refractory and non-refractory gold, and the gold price. Then, the economically optimum duration of bioheap pretreatment, t$, is determined from its logarithmic relation to the optimum fractional extent of ore biooxidation, F$, through the ore's biooxidation rate constant. In doing so, it is assumed that the ore is adequately crushed and amenable to bioheap pretreatment and that the cumulative oxidation of the ore with time is known from ore testing so that the rate constant can be determined.

Jan 1, 1995

By Zhuang Jianming, Liu Qinxia, Yuan Mingliang, Mei Xiangong, Chen Jin

Up to now, the leaching of manganese carbonate ore is usually performed at high temperature of 363K and the leaching rate is lower than 90%. Although in laboratory test, the leaching rate is only 90%. This paper introduced an improved method for leaching of manganese carbonate ore. Certain ammonium salt was added to the pulp to raise the solubility of Mn2+ and reduce the adsorption quantity of Mn2+ on the ore surface. Experimental results show that a leaching rate over 95% can be obtained at the temperature >273K. The activation energy is calculated to be 7.15 KJ/mol and is lower than that of normal leaching technique. The effects of the parameters, such as particle size, pulp density and initial acid concentration on the process results are investigated. A leaching rate higher than 95% can be obtained under the following conditions: particle size below 0.25mm, leaching time 60 min, stirring speed higher than 960 r.pm. H2SO4:MnCO3>1 .2, pulp density 105-205 g.L-l. A kinetic model was deduced, verifying with actual experiments. It showed that the model can describe the leaching process successfully.

Jan 1, 1995

The application of Kirchoff's laws to two adjoining mine ventilation network meshes containing fans results in the construction of two general quadratic equations. These equations may be solved to give the resultant airflows and hence fan duties within the system for given network parameters and fan characteristics. This technique has a wide application for calculating the duties of fans in various combinations within a mine ventilation system. Recent difficulties in economically maintaining environ- mentally safe conditions in underground working areas distant from main ventilation fans has led to increasing interest in the use of controlled partial recirculation of ventilation. This paper develops a recirculation model which can be solved directly using mathematical techniques obviating the need for iterative techniques such as the Hardy-Cross method. The advantage of a direct mathematical analysis is that mathematical algorithms may be constructed to completely describe the ventilation system under a wide range of operating conditions. This technique is applied to controlled partial recirculation ventilation systems to demonstrate its advantages for mine ventilation planning.

Jan 1, 1989

By Y. Topkaya, R. E. Johnson, B. R. Palmer, Bruce E. Kurtz, Anatoli Omelian, John I. Choi

This paper relates to hydrometallurgical studies on the recovery of soluble aluminum values from aluminum-bearing ores, i.e., Georgia clays. At least 50% of the soluble alumina values were recovered by leaching the calcined clays from aqueous solutions, comprising simultaneously contacting a stream containing an effective amount of a reducing agent such as sulfur dioxide and a stream containing an effective amount of an oxidizing agent such as chlorine gas for a time sufficient to dissolve alumina. The recovery of alumina from this aqueous slurry of the calcined clay by leaching with sulfur dioxide and chlorine gas showed much better results than that by leaching with concentrated sulfuric acid and/or concentrated hydrochloric acid at 100O C. The leaching reactions between the aqueous slurry of the calcined clay, chlorine gas, and sulfur dioxide were strong exothermic reactions for several hours, requiring no external heating.

Jan 1, 1993

By A. S. Ibrado, D. W. Fuerstenau

The adsorption of the cyano complexes of Ag(I). Cu(l), Hg(II), Cd(II), and Zn(II) on activated carbon was investigated as a function of pH and correlated with the speciation diagram for each metal. The results show marked changes in uptake with pH, closely resembling the predominance profiles of their neutral and singly charged cyano complexes. Multicharged negative complexes are repelledby the negatively charged carbon surface. The sensitivity of activated carbon to the charge of the adsorbing species indicates that silver adsorbs as an anion, not chemically bound to the coadsorbing counterions. For the same reason, activated carbon is selective to metals that preferentially form neutral and singly charged cyano complexes, namely gold and silver.

Jan 1, 1990

By K. S. Eric Forssberg, T. V. Subrahmanyam

The present paper deals with the important technological developments in gold processing and where possible, the data is presented in the form of tables. Gold processing methods have evolved to such an extent that low grade and complex ores once considered uneconomic are now becoming viable. Constant efforts are underway to innovate technologies in order to improve the efficiencies and cut down the capital and operating costs. The methods are discussed.

Jan 1, 1988

By J. J. Carlson

Studies were carried out to determine whether filtration rate changes observed in an iron ore concentrator were due to variations in particle shape. It was confirmed that ores mined from different locations differed in filtration rates by as much as 60%. However, when image analysis was used to quantify the shapes of the individual particles in the filtration feed, it was found that the particle shapes showed almost no variation, and the shapes did not correlate with the filtration rate. It was also determined that the filtration rate variations were not caused by changes in particle size distribution. These results suggest that the differences in filtration rate are due to factors other than size and shape, such as surface chemistry.

Jan 1, 2008

By J. P. Barbosa, R. V. V. Araújo, R. B. E. Trindade

Bromide stabilizes the auric or aurous ion by forming a stable complex in acidic aqueous solution. The oxidizing agent normally used for the process is bromine, which is a corrosive liquid with high vapour pressure. This is, in fact, the main reason why it has not found acceptance yet as an industrial oxidant for gold. Ferric ion with hydrogen peroxide and/or sodium hypochlorite have already proved to be effective oxidants for the dissolution of gold from a rotating disc in a bromide-containing aqueous solution. In the present work, preliminary tests with four selected ore samples were tested to evaluate the dissolution of gold with the same system already tested with the rotating disc (Br-/Fe3+/H2o2/NaCIO). Compared to the conventional cyanidation, results were superior in one instance only. The major obstacle seems to be the maintenance of a suitable potential to allow the complex formation. However, the studied system may be interesting, is in some situations it may yield better results than conventional cyanidation; therefore, further investigation seems to be worth doing.

Jan 1, 1995

By Russell. A. Smith

This paper describes some recent work on the identification and development of new chemical reagents aimed at improving the industrial processing of phosphate ores by froth flotation. In particular, three chemical product families which will be discussed appear to offer enhanced flexibility by: 1) utilizing a small amount of a silica control reagent which can significantly reduce the amount of anionic (carboxylic) collector required for a given P2O5 recovery level; 2) utilizing a new anionic collector family which offers high P2O5 recovery and selectivity versus standard carboxylic collectors; and 3) utilizing another new anionic collector family which has, in some tests, allowed for selective removal of dolomite from apatite. Examples and use characteristics of each of these new chemical ideas will be presented.

Jan 1, 1993