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By S. Kouniali

Experience with knowledge-based systems for Layout planning and roadway support dimensioning is on hand in European coal mining since 1985. The systems SOUT (support choice and dimensioning, 1989), SOUT 2, PLANANK (planning of bolt-support), EXOS (layout planning diagnosis. 1994), Sout 3 (1995) have been developed in close cooperation by CdF1. INERIS2. EMN3 (France) and RAG 4, DMT5, TH - Aachen6 (Germany); ISLSP (Integrated Software for Layout and support planning) development is in progress (completion scheduled for July 1996). This new software technology in combination with conventional programming systems. numerical models and existing databases turned out to be suited for setting-up an intelligent decision aid for layout and roadway support planning. The system enhances reliability of planning and optimises the safety-to-cost ratio for ? deformation forecast for roadways in seam and surrounding rocks, consideration of the general position of the roadway in the rock mass (zones of increased pressure, position of operating and mined panels). ? support dimensioning ? yielding arches, rigid arches, porch sets, rigid rings, yielding rings and bolting / shotcreting for drifts ? yielding arches, rigid arches and porch sets for roadways in seam ? bolt support for gateroads (assessment of exclusion criteria and calculation of the bolting pattern) ? bolting of face-end zones (feasibility and safety assessment, stability guarantee).

Jan 1, 1996

By G. Mike Bernard

The Andacollo gold mine is located near the town of Andacollo (population 14,000 people) in Chile’s region four. It is about 56km (35 miles) by paved road from the coastal city of La Serena. Santiago is about480 km (300 miles) south. Site elevation varies between 1,000 and 1,280 m(3,300 and 4,200 ft). The climate at the Andacollo site is moderate but arid. Average annual rainfall is only 130mm (5 in.). Because there is little rain and the temperature varies only a few degrees (14 to 24 C or 57 to 75F), there are no problems with freezing, solution dilution or pad saturation. The climatic conditions are ideal for heap leaching.

Jan 1, 1996

The Permian coal in the Muja Coal Measures of Collie Basin of Western Australia has a subdued lustre because of the fine laminations of lithotypes, and the dominance of dull and dull banded lithotypes with minor bright, bright banded and fusinous types. The maceral composition of the coal is variable, however the macerals of vitrinite and inertinite groups dominate and the exinite and mineral matter contents are low. The lithotypes have low concentrations of trace elements and the boron concentration is between 10 - 100 ppm recorded only from the dull lithotypes. On the basis of organic petrology, the inter-seam sediments, flora and the very low concentration of boron, the depositional environment postulated for the coal is braided, fluvial and fluvio-lacustrine with marked fluctuations in the water table. The low water table in the environment accounts for fusain and inertodetrinite in the coal.

Jan 1, 1996

By R. DasGupta

The dissolution behavior of gold in ammoniacal solutions at 75°C has been investigated. The variables investigated include concentration of lixiviants, pH of the solution and various oxidants. The anodic dissolution of gold was studied in the absence of oxidants using the potentiodynamic polarization technique. The cathodic reaction of oxidants was studied on a platinum electrode. Tafel polarization tests were also performed to determine the dissolution rate. The overall dissolution of gold in ammoniacal solutions was examined using a mixed potential theory. A comparative study on the role of cupric am mine, oxygen, hydrogen peroxide, sodium hypochlorite as oxidants for the dissolution of gold in ammoniacal solutions has been carried out.

Jan 1, 1996

By Jan E. Nesset, L. Paul Staples

"High Gradient Magnetic Separation (HGMS) technology, although developed over 2 decades ago, has not been widely applied to the separation of sulphide minerals. Under conditions of strong magnetic field gradients, weakly magnetic minerals such as chalcopyrite (CuFeS2) and marmatite (Zn(Fe)S, sphalerite with iron in solid solution) behave paramagnetically and can be effectively separated from diamagnetic minerals such as galena (PbS). The application of this technology to the separation of Cu-Pb and Zn-Pb bearing streams in the treatment of fine grained complex sulphides may in some cases be more effective than separation by flotation. A 2 TPH Sala HGMS pilot plant was operated at Brunswick for a nine month period, ending in March 1995. The testing demonstrated the mechanical reliability of the technology, the consistency of operating results and the scale up from laboratory testing. HGMS is seen as a complimentary technology to flotation, best suited to performing those separations of galena (and other diamagnetics) which flotation does not do as well.IntroductionBackgroundSince the turn of the century, the magnetic character or magnetic susceptibilities of minerals have been determined with increasing precision and accuracy. Figure 1 illustrates specific magnetic susceptibilities of some common minerals. As long as susceptibility ranges do not overlap, separation is possible.In 1937, the principle of using a magnetizable matrix material in a magnetic field to increase both magnetic flux density gradients and number of capture sites for susceptible minerals was first applied (Frantz). It was not until the 1970's, however, that the genuine development of wet high gradient magnetic separation began with the introduction of very fine matrix materials to the magnetized volume of large solenoid magnets. Today, dozens of HGMS units purify, filter and separate minerals, primarily for the removal of iron stained minerals from clays used in the paper coating and china clay industries and for the recovery of fine titanium and iron oxides in the iron ore industry. Only the Garpenburg mill in Sweden is currently applying a continuous HGMS machine to separate complex sulphide minerals; upgrading a lead concentrate since 1988."

Jan 1, 1996

There are countless petroleum and mineral fiscal systems throughout the world. This is because many petroleum and mineral producing countries have developed their own methods of calculating government take through fiscal evolution or individual negotiation. Those countries fortunate enough to have petroleum and mineral reserves within their national boundaries are naturally reluctant to yield this resource without a reasonable return for their population. As resource companies are perceived to be enormous conglomerates with endless amounts of cash and resources, governments and the general public demand reasonable division of production while these finite resources last. On the other hand, because companies engaged in the exploration for, and production of, minerals, oil and gas have to be large or lucky (preferably both) to sustain the great physical and commercial risks involved, the income and profit figures look so large that the general public sees them as an acceptable target for taxation. Taxation of the resource industry has been one of the industry's greatest cash flow problems through the years. Allen and Seba (1993) attribute this to the fact that the most equitable tax systems are those that affect the widest possible total of the population.

Jan 1, 1996

By Peter Cain

Longwall extraction in the Phalen Scam in the Sydney Coalfield of Nova Scotia is carried out under flooded abandoned workings in the Harbour Seam 140 m above, and at depth of up to 700 m beneath the Atlantic Ocean. Careful planning of panel and pillar dimensions is necessary to prevent inflows from the overlying workings and to prevent the development of excessive subsidence strains at the seabed. This paper briefly summarises the research undertaken over the past five years by CBDC and CBCRL into the problems associated with mining under water, and then describes the development and application of a design/planning code of practice developed jointly by CBDC, CBCRL and mine regulatory agencies. The design method employed in the Code of Practise is based on empirical data from the coalfield and parameters developed from subsidence modelling and previous water inflow experience. It includes precautionary measures to be adopted during development and mining, and monitoring procedures to be followed. It is flexible enough to allow future developments in the understanding of inflow mechanisms to be incoporated without major modifications, and represents a major step forward in reducing the potential hazards associated with coal extraction in the coalfield.

Jan 1, 1996

By G Eastwood, C Joyce, P Ryan, G M. Johnston

Over the years, predictive techniques for Acid Mine Drainage (AMD) and the natural processes affecting acid generation have received considerable attention. Less emphasis has been placed on the sampling strategy and the integration of testwork results with the geological data base. The sampling strategy employed and the development of a geological model to determine the spatial distribution and volume of acid producing material are often crucial for developing cost-effective containment and mitigation measures. The geological model provides a link between the occurrence, timing, destination and placement of mined waste rock. Careful and accurate interrogation of a comprehensive geological database provides this linkage. The AMD testwork program at Cadia in NSW has been designed to identify the temporal selective handling requirements that will be required during operation. Sampling involved collection of representative combinations of all waste rock types identified within an extensive geological database. These samples were subjected to static, kinetic and accelerated weathering predictive tests. Preliminary results have been used to construct a waste block model for the deposit that identifies the quantity and distribution of acid producing material. Integration of the block model with the mine scheduling determines when the material will be mined.

Jan 1, 1996

By Johnson G. D

Confidence in Yakabindie becoming a truly cost competitive nickel project has risen recently because of: ò the emergence of an economically effective contract mining climate; ò the delivery of cheaper energy via the Goldfields Gas Pipeline; and ò the development of the Yakabindie Process for production of nickel cathode and cobalt by-product directly from sulphide concentrates at site, dramatically cutting capital and operating costs compared to the conventional route. Development of the Yakabindie Process was a result of 'necessity being the mother of invention'. Yakabindie can now break out of the trap of relying on existing downstream processors to treat an intermediate, and instead the project can gain direct market access. The very attractive cost advantages demonstrate that hydrometallurgical processing of sulphide concentrates is a worthy prize. Improved cobalt recoveries, and tolerance of higher levels of magnesium and arsenic than allowable by smelters, are further advantages of this approach. Leach residues are combined with much larger quantities of naturally alkaline flotation tailings and remain at site. As a result the process is more environmentally sensitive than the conventional smelt/refine route, with no sulphur dioxide gas emissions and 'metal only out the gate'.

Jan 1, 1996

By Bailey S, Avraamides J

Laboratory-scale experiments were conducted in a mechanically stirred aeration vessel to determine the rusting abilities of aerated water in the presence of various catalysts compared to the industrially used ammonium chloride. The catalysts used were tartaric acid and citric acid, firstly by themselves, and then in later experiments mixed with ammonium chloride. From these experiments it was found that leaching of iron from reduced ilmenite in the presence of either tartaric acid or its sodium salt was much slower than in the presence of ammonium chloride. Citric acid or its sodium salt also give a slower rate of leaching than the ammonium chloride system, but citric acid and its sodium salt mixed in equal proportions produced a rate of leaching approximately twice as fast as the standard ammonium chloride system. When tartaric acid was mixed with ammonium chloride the leaching rate was found to be equivalent to the leaching rate of the same amount of ammonium chloride alone, thus indicating that tartaric acid made no contribution to the leaching in this svstem_

Jan 1, 1996

By Jorgen Elbrond, Xiaoli Tang

In this paper we apply continuous-time option pricing theory (Dixit 8 Pindyck 1994) to show how to obtain an optimal investment rule for a mining project which requires sequential in- vestments. The application per se is to some extent very simple. The main purpose of the paper, however, is to draw the attention of mining people to how the option pricing theory may be used to capital investment decisions. This topic in economics is quite new but is attracting a lot of attention.

Jan 1, 1996

By P. Tsang, S. S. Peng

The stability of longwall chain pillars depends not only on the mechanical properties of the coal and surrounding rocks but also on geological and mining conditions. To evaluate the effects of each variable, orthogonal experimental design was employed in a significance analysis. The study concluded that the stability of longwall chain pillars is mainly controlled by the ratio of pillar stress to pillar strength, the ratio of the Young's moduli of roof to coal and floor to coal, entry width, pillar width and the internal friction angle of coal. Additionally, horizontal stress, panel width and mining height also play a significant role.

Jan 1, 1996

By S. R. Reddy, R. G. Reddy

"The Margules equation is used for interpreting excess Gibbs energy of several ternary systems. In the present study activity coefficient of a dilute solute, 2, in a binary solvent 1-3 was derived. The derived expression is used to interpret logarithmic activity coefficient of oxygen and sulfur in several metallic systems. Self interaction parameter of the solute is derived from the partial function of solute using constant compositional path. An expression for logarithmic activity coefficient and self - interaction parameter of solute is also derived using Maclaurin infinite series. The derived equation is based on Maclaurin infinite series used successfully to deduce thermodynamics of self interaction of oxygen as a interstitial atom in two metallic systems. The predicted thermodynamic parameters values using Maclaurin infinite series and Margules equations, are in excellent agreement with the experimental data and also our predictions are far more accurate than the predictions made by other models.1 IntroductionIn most of the pyrometallurgical high temperatures processes, interactions of solutes such as oxygen, nitrogen and sulfur, with the solvent atoms are most important during refining processes. There are numerous theories are developed [1-25] to interpret the thermodynamics of solutes in multicomponent alloy systems. Which are mainly developed using statistical or Quasichemical equations.Wagner [4] developed one energy parameter ideal solvent model based on activity coefficient of solutes compositional dependency. He used one energy interaction term which is not able to account for interaction energy parameters for the same solute concentration at different solvent compositions and also it is ineffective model to predict for strong interacting systems."

Jan 1, 1996

By Paul Worsey, Ron Ecklecamp, Scott G. Giltner, Ronnie Inman, Terry Drechsler

A blast monitoring program conducted at Chemical Lie Company’s new lime calcining facility near Ste. Genevieve, Missouri is discussed. The purpose was to develop blasting criteria for the construction and operation of the lime plant within the quarry operated by Tower Rock Stone. Further, it was imperative to accommodate production requirements into the blasting criteria. The major concern was the effect of blasting on the curing of green concrete during the construction of the storage silos and kiln stacks. In addition to discussing the susceptibility of curing concrete to blast vibrations, the paper also details how this varies with time.

Jan 1, 1996

By E. Topuz, J. Mastoris

The problem of defining the optimum final limits of an open-pit mine has challenged the mining industry for the last three decades. The difficulty results mainly from the great number of variables involved and from the sheer computational effort required in real-life applications. An actual lignite deposit is used in this study to introduce and apply a new methodology that can be used as a basis for surface-mine design optimization. A geologic-reserves model of the deposit is first developed with the use of an integrated geostatistical-modeling package. The model is transformed into an economic one through the use of flexible objective function formulation(s). The final open-pit limits are then optimized using a competent commercial optimizer, and comparative-sensitivity analyses are performed to study the effect of some basic mining and economic parameters on the optimal pit design. The conclusions drawn can develop useful guidelines for decision making by the mine operator.

Jan 1, 1996

By P. D. Rao, D. E. Walsh, W. W. McClintock

A column flotation system was designed to conduct release analyses on a very finely disseminated, stratiform copper ore from the Denali Copper Prospect in Alaska. Chalcopyrite is finely disseminated in a carbonate matrix, and pyrite is disseminated in both the chalcopyrite and the gangue. Grinding to -20 µm is required for adequate liberation. A 25-mm x 2.4-m glass flotation column was designed. The ore and its flotation tailings were repeatedly floated to obtain a rougher concentrate. The rougher concentrate was then repeatedly floated to produce release fractions. These fractions were analyzed for copper, iron, calcium and magnesium, and release curves were plotted. The procedure was replicated at each of two grinds, i.e., 99% and 88% passing 37 µm (400 mesh). The procedure should find application for flotation characterization and process selection. Bond grindability testing was also conducted.

Jan 1, 1996

By J. Shahabpour

"Many porphyry copper deposits of the Kerman copper province in central Iran are associated with a consistent structurally con-trolled main drainage pattern, which is shown in this paper to be a useful regional prospecting tool in the search for new deposits. The main drainage trends also generally allow the distiction of high-grade (>0.2% Cu) from low-grade (<0.2% Cu) deposits. Topographic maps1:50 000 or geologic maps 1:100 000 have been found suitable for identification of promising drainages.IntroductionTrends of the main drainage systems transecting the high-grade porphyry copper deposits of the Kerman Region in Iran coincide with Quaternary age regional faults and fractures. Observation of such drainage trends can expedite regional evaluation prior to field examination. Thirty deposits located in the Kerman Region (Fig. 1) have been studied to identify common features that can be used for exploration purposes, especially for the first stage of regional exploration. A variety of field criteria are available for subsequent rapid field checking prior to trenching and more costly methods such as drilling, etc.Characteristic geomorphic features have been considered as aids in mineral exploration by many authors (e.g., Faniran, 1971; Piotrovski and Lubkashov, 1976; Verstappen, 1983). Clark et al. (1967) indicated the relationship between geomorphology and the supergene enrichment of copper in Atacama Desert, Chile, and correlated three periods of supergene enrichment with three periods of pediment disection. Seeland (1978) used fluvial drainage patterns for uranium and hydrocarbon exploration in the Wind River basin, Wyoming. Postolenko and Konopleva (1973) used the reconstruction of ancient valley systems for exploration of gold placers"

Jan 1, 1996

By R. C. Hubli

Copper (II) chloride has proven to be an efficient lixiviant for copper sulphide ores and secondary sources of copper such as scrap. Nickel sulphides are generally associated with copper ores and copper-nickel matte is an intermediate product of processing mixed sulphides. While the copper species in aqueous chloride media are present as chlorocomplexes, the presence of nickel as Ni++ offers effective separation between the two by solvent extraction techniques. Oxidation of millerite by cupric chloride in sodium chloride solutions has been studied as a function of rate of agitation, leaching time, temperature, acid concentration and total initial cupric concentration. The reaction has a 1/2 order of dependence on initial cupric concentration in the range of 0.0 to 0.5M. The activation energy for the temperature range 333 -363 K has been found to be 59.2 kJ/mol with chemical reaction at the unreacted mineral surface as the rate controlling step. The rate expression, according to the shrinking-core model, for initial cupric concentrations between 0.0 to O.5M, is evaluated as

Jan 1, 1996

The 99th Annual General Meeting of The South African Institute of Mining and Metallurgy was held in the Gold Room, Transvaal Automobile Club, 60 5th Street, Lower Houghton, Johannesburg on Wednesday, 14th August, 1996. Obituaries The President announced the death, during the year, of the following members: Life Fellows H.L. Munro, H.S. Simpson, P.L. Ward Fellows I.M. Hossy, A.E. O&apos;Meara Retired Fellows E.A. Arvidson, R.F. Bourne, F. Hawke, W. Lloyd, J.M. Meyer Members J. Allen, P.A. Boardman, L.M. Jacobs, G.F. Marx, G.D. Perry, R.W. Spraggs Retired Member M. Milner Associate I. Pieterse. In memory of the deceased and in sympathy with the bereaved, all rose and observed a moment of silence.

Jan 1, 1996

By J. Bender

The objective of this research was to (1) Further develop cyanobacteria mats&apos; for metal-tolerance and cold-tolerance, (2) test them for durability in the field environment and (3) assess them for metal sequestering potential with actual and simulated field samples. Results show that mats performed well In the field and effectively sequestered metals from actual and simulated field samples. Metal uptake from Iron Mountain Hine samples was for Ins 87%, Cu and Cd 99%, Initial concentrations (mg/L) were Zn = 3,250, Cu , 279, Cd = 28. In solutions simulating the Gulf Tunnel drainage, Zn and Mn were effectively removed by mats immobilized on glass wool. Effluent water, after treatment, generally had a Ph of 7 .5-8.5. Al though the final metal concentrations in the mats &apos;harvested from the decontaminated water were only 1% or less, the actual mechanism of metal deposit was probably a mat-mediated alteration of the environmental conditions causing the metals to deposit outside the mat as oxides or carbonates. Bioflocculents, released by the mats, were likely involved in the metal-removal process.

Jan 1, 1996