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By Paterson M. R, Spencer P. A

Vitrokele technology is a resin process that can be applied in gold plants to reduce both capital and operating costs. The Vitrokele resin can be used for both precious metal recovery and for recovering free and combined cyanide from effluent streams. Vitrokele resin has been extensively tested at pilot plant level and is now applied successfully at a commercial heap leach facility in Zimbabwe where it is used in place of activated carbon for recovery of gold from pregnant leach solution. Significant capital cost savings were achieved by installation of a resin plant instead of a conventional carbon adsorption plant. Operation to-date has not seen any significant physical or chemical degradation of the resin either in terms of adsorption capacity/kinetics or physical appearance/size. This gold recovery process is equally applicable to slurry streams where it would be implemented in stirred tanks with interstage screens in a similar manner to a conventional carbon adsorption plant.

Jan 1, 1996

This paper attempts to put into perspective the implications of the legal disclosure requirements for promoters and consultants when making statements concerning ore resources and reserves. The need to take account of non-technical as well as technical factors is highlighted.

Jan 1, 1987

By G E. Smith, G N. Lye

Wall control blasting practices are necessary to reduce the impact of blasting on mine faces but can also have a significant negative impact on mine productivity and operating costs. The conventional practice in deep open pit mines is to use so-called trim blasts adjacent to pit walls. To provide burden relief these trim blasts have fewer rows than full production blasts and are fired to a cleared free-face; hence they are termed æunchokedÆ. This practice leads to scheduling constraints on the pit operations and can cause ore dilution due to excessive muckpile movement. The use of such trim blasts stems from the perception that increased wall damage results from æchokedÆ blasts. These concerns are based on the unproven assumptions that blast vibration levels and explosive gas penetration increase with increased blast burden and face confinement. This paper describes work undertaken as part of a major investigation into wall control blasting at the KCGM Fimiston Mine, Kalgoorlie, Western Australia. It details a study to assess damage effects due to blast burden. Borehole air pressure measurements and borehole video camera inspections were done behind a series of single blastholes drilled with varying burden distances, as well as behind a dedicated trim blast and a full production blast. It was found that the measured damage effects, including visible rock cracking, dilation, and the limited extent of gas penetration behind the blastholes, did not vary significantly with burden or blast type for the cases tested. This result was in complete agreement with detailed vibration measurements conducted by Blair and Armstrong (2001) during the study, which found that vibration was independent of blast burden. As a result of these investigations, changes to the blasting practices at the mine were implemented. Dedicated trim blasts and free-face blasting have been replaced by modified production blasts and the practice of æchokingÆ blasts has been introduced. This has resulted in a significant improvement in productivity and cost savings without compromising pit wall integrity.

Jan 1, 2001

By Espinosa-Gomez R, Johnson NW

The Copper Concentrator at Mount Isa Mines Limited treats on average 18 000 tonnes/day of chalcopyrite ore containing typically three per cent copper. The main gangue minerals are iron sulphides (-13 per cent) and non sulphide gangue (-78 per cent). In August, 1991, the comminution flowsheet was changed from a conventional circuit (crusher/rod mill/two stage ball milling) to a modem circuit (fully autogenous grinding/one stage ball milling). The 80 per cent passing size of the flotation feed with the conventional circuit was 125 microns. The Copper Concentrator has two parallel grinding lines, two roughing and scavenging flotation lines, and common cleaning, recleaning and retreatment sections. During the first six weeks of the installation phase, one of the two flotation lines was fed by the conventional grinding circuit and the other by the autogenous grinding circuit. Data from parallel surveys and historical data are used to analyse the rougher/scavenger flotation performance before and after the change. The solid and mineral distributions of the flotation feed, the pulp chemistry and the reagent requirements are compared. The mineral liberation before and after the installation of autogenous grinding is compared on a sized basis using data from the 14 consecutive months before, and the seven months after the change. Liberation was measured using the QEM*SEM(*) instrument. The overall effect of the new grinding circuit on the plant metallurgy is also assessed using the copper recovery values, the dilution of the final concentrate and the distribution of copper losses in the final tailings. (*) Quantitative Evaluation of Materials by Scanning Electron Microscopy

Jan 1, 1993

By Morris A. E

The thermodynamically-based pyrometallurgical simulation software STEPSOL (Version 3.0) provides for the modelling of activities using the Interaction Parameter Model, the Regular Solution Model, the Sub-Regular Three Suffix Margules Model, the Sub-Regular Four Suffix Margules Model and various simpler polynomial models. These are briefly reviewed, along with the major sources of data available in the literature, and the implementation of the models in the program.

Jan 1, 1992

The continuous casting of zinc alloys has been of fundamental importance for many years in the production of a number of products, including sheet for architectural applications, battery cans for dry cells and wire for metallising. The intrinsic benefits of continuous casting, including efficiency and high tonnage capability, uniformity of metallurgical structure and properties, and absence of voids and other defects, have contributed to the success of these products. Less well known, but of growing importance, is the more recent application of continuous casting technology to the production of zinc alloy bar stock products, including bearing stock, machining bar stock, forging stock and cathodic protection anodes. A wide range of zinc alloys are now continuously cast in a variety of cross sectional shapes and sizes to suit the diverse characteristics of these products. Of particular significance are the introduction of hollow zinc-aluminum bearing stock, and the availability of zinc alloy machining bar stock for hydraulic applications and for producing prototypes of zinc alloy pressure die castings. In addition to the traditional benefits, continuous casting provides special properties which are important in the application of these bar stock products. The list of successful applications of continuously cast zinc alloy bar stock is growing rapidly, and the market potential for resultant new zinc applications appears to be significant.

Jan 1, 1993

By M Simanjuntak, A M. Supomo

PT Freeport IndonesiaÆs copper/gold operation disposes of approximately 222 000 dry metric tonnes of tailings per day via two thickeners. Reduction of the flocculant dosage rates in each of the tailing thickeners has been achieved with the installation of Clarometers«, modifications to the existing operating DCS control strategy and a change in plant flocculant. This has reduced the flocculant consumption rate in the last twelve months by approximately 20 per cent. It has also highlighted the disparity in the settling rates of the two thickeners. Collaborative efforts between Cytec technical site engineers and Freeport operational personnel have made possible the overall gains achieved in the tailings thickener optimisation.

Jan 1, 2003

Australian coal mines have spent considerable capital on dragline improvements over the last two years. This has included ~$30 M on UDD conversions, >$20 M on new buckets, boom upgrades, electrical upgrades, etc. This is a natural part of the response of mining companies to technology and replacement programs. Capital expenditure is a normal part of the ongoing success of most companies. There is however, a tendency for some people to rely on the capital alone to provide the ongoing improvements in equipment productivity. Implementing new technology through capital expenditure is only part of the equation in continuous improvement. For 80 - 90 per cent of the year, the operator controls the productivity achieved by the dragline. Variation between operators is huge. The average standard deviation in productivity is 12 per cent and maintenance impact is over 40 per cent. Robbins 2003, states: Contrary to what we were taught in grade school, we werenÆt all created equal. Most of us are to the left of the median on some normally distributed ability curve. Further, he states: The issue is knowing how people differ in abilities and using that knowledge to increase the likelihood that an employee will perform his or her job well. There are two options for reducing variability between operators; improving operator ability and getting the machine to take over what the operator is doing (automation). Dragline automation will be discussed, however, this paper will focus more on the æhuman factorÆ and how to establish a dragline with minimum variability between operators.

Jan 1, 2005

By Grader F. E

A linear motor properly wound can serve as a mechanism for separating paramagnetic sulphide minerals, like pyrrhotite, from other sulphides and associated gangue minerals. The effective- ness of separation depends on the energising current of the separator, the frequency of the a.c. cycle, and the particle size of the minerals. The speed of travel of the minerals over the surface of the separator is also a function of particle size, and appears to be constant. The movement of pyrrhotite, magnetite and iron filings of comparable size fraction (150um +74pm) on the linear motor surface has been observed using a cine camera. An attempt has been made to give a theoretical basis for the movement of the particles by calculating the minimum electrical energy required to move them. Further, the rate of decay of magnetic moment of the particles has been estimated for magnetite and it has been found that sufficient residual magnetism existed in the particles after they had been exposed to the first half of an a.c. cycle for them to have like polarity with the second half of the cycle. The particles are therefore repelled from the motor surface every second half of the cycle. This repulsion due to remanent magnetism is the probable cause of particle movement over the linear meter surf, e.

Jan 1, 1980

Diamond drilling was first carried out at Norseman in the Princess Royal Mine, early in this century. Little concentl'ated drilling was done from then until Western Mining Corporation commenced drilling in 1934. Since then Central Norseman Gold Corporation N.L. has continually employed diamond drilling in exploration of the field. After 1946 the advantage was seen of applying broad pattern surface drilling at Norseman in the reef exploration. In 1953, as a result of the steeply rising cost of drilling and the time taken to penetrate surface material by light equipment, heavier drills and new rigs were introduced. The surface drilling programmes called for a greater monthly or annual footage and to satisfy this new techniques were introduced. The Mitchell-21 machines were discarded and A-3000 machines were installed, firstly under a 48 ft. fixed tower, then mounted on a truck with a 20 ft. tower, and finally on a truck carrying a 40 ft. tower. With the mobile units a compressed air compressor is attached. By use of compressed air with either the Reed roller or Hawthorne bit, rate of penetration of overburden is greatly increased. The mobility of the truck mounted machines has greatly reduced the time required to move from one hole to another, and the use of heavier machines on a three shift per day basis has considerably increased the footage per shift. The general result is an increase to 1,500 ft. of drilling per month per machine, while costs have been greatly reduced in spite of increased wages and diamond prices.The underground drilling technique is described. Analysis of performance has not been made because the drillers performance is subject to shaft routine and service.INTRODUCTIONGold was first discovered at Dundas in 1894, and at Norseman, 14 miles north, in 1895. From that tirpe until 1935 mining activity fluctuated. Following the mining revival in 1935, production in the field has remained comparatively stable. This stability in part has been due to the broader scale of operations of Central Norseman Gold Corporation N.L., and in these operations diamond drilling has played an increasingly important role.

Jan 1, 1956

Cerro Matoso (CMSA) in Colombia produces ferro-nickel from lateritic ore containing approximately three per cent nickel, using a Rotary Kiln - Electric Furnace (RKEF) process, in which the calcining of the mineral within the kiln is second in importance only to the smelting of the mineral in the Electrical Furnace. This article discusses the installation and operation of an expert system to control the kiln of CMSA. In the CMSA process, the run-of-mine ore is crushed, homogenised, dried and mixed with a small percentage of coal, before being heated up to 900¦C in a rotary kiln in the presence of natural gas mixed with air in a controlled proportion (air/gas constant ratio). The final objectives of the process are the following: ò To reduce to a minimum the iron and nickel oxides in order to convert these into metallic ions; this is a reduction process to facilitate largely the smelting in the electric furnace. Since the reduction is made with natural gas, it is much more economical than the subsequent complete reduction in the electric furnace, since electrical energy is much more expensive by unit of processed mineral. ò To heat the mineral as much as possible to facilitate the subsequent smelting. ò To eliminate totally the moisture content of the ore. An expert system with fuzzy logic was commissioned in 1994 for the control of the kiln and it has operated with good results ever since.

Jan 1, 1996

Industrial minerals and rocks (alternat ively called non-metallic minerals) are those- which are economically important because of their desirable physical or chemical properties rather than their metal or energy content. They are divided into nine classes: structural, pig- ments, process aids, ceramics and refractories, chemical source minerals, abrasives, foundry minerals, gem stones, electrical minerals. Development of deposits is influenced by the dominance of marketing,by the required range of products, the-need for specialized process- ing, place value, and the transportation and distribution of high-bulk, low-cost commodities. Evaluation is different from that of base metals because of differences in geological occurrence, sampling methods, testing, treatment, placing a money-value on the material and the importance of export markets.

Jan 1, 1973

By Sheridan GD

Fifteen samples 'of clays and shales from the Adelaide area were selected from a total of 84 as representing material of possible value for the manufacture of light-weight aggregate. A detailed examination of the bloating. characteristics of these revealed four likely to be suitable. for expansion.' in a rotary kiln. One of these, a Tapley. Hill shale., was-fired in an 8 in. diameter rotary kiln, but con-tinuous bloating without ring formation in the kiln was not achieved. Steam,,-oxygen,, sulphur dioxide and carbon dioxide have been, suggested. as the agents of bloating. An examina-tion of .. the evidence : `leads to the conclusion that carbon dioxide derived from. carbonate minerals is likely to be the principal bloating agent. Attempts to bloat clays by the addition of mica were.not successful.

Jan 1, 1963

By M J. Pascoe

The performance of 460 stope surfaces at WMC ResourcesÆ Olympic Dam Operation (ODO) has been used to investigate the confidence that can be placed in the Stability Graph Method for design of stope dimensions. A detailed database of stope performance and ground condition information was established for each stope. The database contains all the required stability graph information as well as other factors thought to influence stability, such as discrete major structures, poor shape and exposure time. The performance of each stope surface was quantified by calculating Equivalent Linear Overbreak/Slough (ELOS). The performance of stope walls and crowns was plotted on the supported and unsupported case history stability graphs. Based on this information an ODO design limit of HR = 3.3 x NÆ0.33 has been suggested for stope walls. Walls that plotted above this line were 80 per cent stable, 20 per cent unstable and zero per cent failed. Below the line 60 per cent were stable, 30 per cent unstable and ten per cent failed. Supported crowns that are flat or arched in shape and are not within the influence of major structures can be designed in the stability graphÆs æstable zoneÆ with a strong likelihood of stability. The Stability Graph Method did not reliably predict the performance of unsupported crowns at ODO.

Jan 1, 2005

The Tavua Power Proprietary Ltd. was created in 1936 for the purpose of supplying electric power, compressed air and water to the mining field.The original share capital was subscribed on a two-third:one-third basis by the Emperor Gold Mining Company Ltd. and Loloma (Fiji) Gold Mines, N.L. In 1940, Fiji Mines Development Ltd. (later changed to Dolphin Mines Ltd.) was admitted as a shareholder, and, in 1950, a further change occurred. The present shareholding in the Company is as follows:A central power station was decided upon to reticulate power and compressed air over the whole field and building commenced in May 1936.The original plant comprised three Belliss and Morcom diesel generating sets 770 b.h.p. 525 kW 3,300 V, 3 phase, 50 cycle; one Belliss and Morcom diesel compressor set 2,09'0 cu. ft. of free air per min. at 90 lb. gauge 300 r.p.m., and two small Ruston-Holman diesel compressor sets each of 525 cu. ft. capacity taken over from Loloma (Fiji) Gold Mines, N.L., and the then existing Koroere Gold Mining Company.BuildingThe original building was 130 ft. long by 47 ft. wide with an elevated switchgear annex on the west side from which a clear view of the engine room is available.

Jan 1, 1953

By Morris A. E

The thermodynamically-based pyrometallurgical simulation software STEPSOL (Version 3.0) provides for the modelling of activities using the Interaction Parameter Model, the Regular Solution Model, the Sub-Regular Three Suffix Margules Model, the Sub-Regular Four Suffix Margules Model and various simpler polynomial models. These are briefly reviewed, along with the major sources of data available in the literature, and the implementation of the models in the program.

Jan 1, 1991

Geological models for the exploration and evaluation of epithermal Au and porphyry Cu-Au deposits rely upon a classification of different deposit styles and an understanding of the evolutionary processes of deposit formation. These models guide the interpretation of subsurface deposit anatomy in order to target drill testing and assist the explorationist to focus on the more prospective projects. It is important for the explorationist to distinguish between different styles of magmatic arc Au deposits as each style displays distinctive characteristics with exploration implications. Magmatic arc Au deposits are distinguished as porphyry Cu-Au formed at depths of 1 - 2 km at the apophysis to larger, buried, magmatic sources which are also the ultimate metal sources for the varying styles of shallower level epithermal Au deposits. Low sulfidation epithermal Au deposits characteristically develop from dilute circulating meteoric waters and are distinguished as the group with a closer relationship to intrusive source rocks, and slightly higher sulfide contents (still generally

Jan 1, 2004

The products of Lower Miocene calc- alkaline activity on the east coast of Northland, New Zealand are described and contrasted with coeval rocks of the northern North Island. These rocks, the Eastern Volcanic Belt (EVB), occur in four main centres aligned north-west to south east as either plutonic/hyabyssal bodies or as agglomeratic piles and dyke intrusions. Significantly the plutonic members always occur to the north-west of the volcanic members, probably indicative of differential uplift along faults (upthrown to the north) aligned perpendicular to the EVB. A full basalt-rhyolite (diorite-granodiorite/ adamellite) spectrum is represented, with a temporal progression towards the silica-rich endmembers indicated by cross-cutting field relationships. Modal mineralogy parallels this trend, consisting of two-pyroxene, hornblende, biotite, quartz/alkali feldspar modal assemblages, and with rare occurrences of olivine and garnet-bearing volcanic phases. Chemically the EVB is medium-K, calc-alkaline (with respect to AFM and total-Fe/MgO vs. Si02 indices) and quartz and hypersthene normative. The thirty two available K-Prisotope dates indicate that activity was largely confined to the Lower Miocene (24Ma-16Ma), with an apparent younging towards the south east. Initial B7Sr/e Sr ratios (0.70335- 0.70679) are indicative of a continental- arc-type setting, however it is unlikely that a straightforward tectonic reconstruction for this part, of the Pacific Margin is possible. Evidence from xenoliths, both petrologic and isotope, within EVB magmas and from regional geologic studies suggests that hypotheses pertaining to a volcanic arc sited over a subduction zone may hold little relevance in this case. The review concludes that the EVB developed from the partial melting of a geochemically evolved lower crust as indicated by xenolith evidence. This occurred in response to thickening initiated by a short-lived obductive event in the uppermost Oligocene, and controlled spatially by pre-existing basement structure. Intra-suite chemical and mineralogic variation reflects not only crustal variability, but localized differences in physico-chemical conditions best illustrated by the rare occurrences of olivine and garnet.

Jan 1, 1987

The coastline is. an incomparable stretch of sea coast known as Ninety Mile Beach. Two gas pipelines and two oil pipelines carrying hydrocarbons from thb'Bass Strait fields to the markets of Australia cross this beach. They cannot be seen as they are laid in trenching stretch- ing many miles out to sea and the beach was restored to its natural state. Even where the dunes were disturbed, suitable grass was sown thus consolidating the sand and preventing erosion. Ninety Mile Beach is but one of the many key.wildlife and recreational areas that our operations must be concerned with. Others include Westernport and Corner Inlet, but the one discussed in this paper in particular is the platform area of the Bass Strait itself. Never was the old adage "an ounce of prevention is worth a pound of cure" more meaningful than in offshore oil production. All are well aware of some of the events of the past several years that resulted in large and costly oil spills. Far less is known, seen or publicised about the measures and developments that are undertaken to ensure that such events do not occur. We also have well developed plans for response in the event of an emergency situation, which can be initiated with great rapidity. Our responsibility is to ensure that with the best of engineering technology and operating procedures, spills do not occur.

Jan 1, 1971

By Mutmansky J. M, Hartman H. L

Multiple operating points for mine fans are a problem that fan and mining engineers must constantly be aware of in mine/fan systems. In a single-fan system, unstable conditions can be avoided by restricting fan operation to the "normal operating range." When mine fans are operated in parallel, the situation becomes a little more complicated. Multiple operating points are more often encountered and the fan user must be aware of these multiple points to have a suitable set of operating conditions. However, for fans in parallel, the engineer can plot the combined characteristic in a relatively straightforward manner and thus can avoid conditions that would cause instability in the mine/fan system.

Jan 1, 1988