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The major copper orebody at Mount Isa is being extracted at a rate of four million tonnes per year. The method used requires an equivalent rate of back filling with (mainly) cemented fill. There were three major incentives for developing this mining system. The first was the prospect of high ultimate recovery of the orebody. The target is 100 per cent recovery. Also the proposed stoping layout appeared to offer significant advantages in development and production costs. Finally, extensive subsidence above the northern end of the orebody could have disturbed permanent surface installations and jeopardised a possible future open cut. The full implications of this ambitious strategy were not apparent in the early years. Now, after 12 years of production the benefits are being realised and they can be weighed against the costs. Probably the most interesting result which comes from this analysis is the significance of cutoff grades and dilution factors in balancing mining and filling rates.

Jan 1, 1980

Alluvial gold mining in New Zealand and in particular on the West Coast underwent a renaissance during the early 1980's. This was based on two main factors: a) the sharp rise in the gold price b) the advent of the hydraulic excavator with which to mine the auriferous gravels. The scale of operations varies considerably. A small operation typically consisting of one or two people using an excavator to feed either a land based or pontoon mounted (floating) gold recovery unit, which will typically feature a rotary screen with or without a tailings stacker with the screened fines < 10 - 15 mm) fed over riflle tables. The largest screening plants of this type are operated by DML Resources in their Arahura and Mikonui mining operations where the plants have the capacity to screen up to 250 m3 of gravel per hour. These plants usually employ jigs and centrifugal concentrators for gold recovery. Unique amongst current operations is the Grey River Dredge, a bucket ladder dredge capable of processing 700 m3 per hour similar to those that operated earlier this century. Gold concentration is by a series of jigs. The number of plants operating in recent times peaked at around 130 in 1987 (coinciding with a nominal average gold price of $751) and since that time has steadily declined to 80 units in 1993 and about 45 - 50 units today. This cycle of rapid expansion and then steady decline has been repeated on the West Coast since the original gold discoveries in the mid nineteenth century.

Jan 1, 1996

By Ralph B. J, Sadler W. R

Thiobacillus ferrooxidans was shown to catalyse biodegradation of chalcopyrite concentrates. The process was growth associated at normal temperatures (30°C) in dilute acid solution (pH2, H2SO4) in submerged cultures. Approximately 20% of the copper dissolved in 22 days in the presence of T ferrooxidans while less than 0.6% was released when bacteria were absent. In ore column leachates, the iron and sulphur oxidizing species T ferrooxidans, ranged from I04 to I06 cells/ml while exdusively sulphur oxidizing species ranged from I02 to 104 cells/ml. T ferrooxidans predominated below pH 3 while other sulphur oxidizing bacteria favoured higher pH. Organisms were distributed vertically in ore columns according to pH differences, resulting from gradual acid consumption by gangue, during trickle irrigation.There was a sequential development of bacteria in leachates from fresh ore irrigated with water only. High pH sulphur oxidizers were always present, low pH sulphur oxidizers appeared within a week while T ferrooxidans took 50 days to show up. Routine monitoring of bacteria in dump leachates provided a qualitative indication of events in otherwise inaccessible ore bodies.

Jan 1, 1981

Recovery of Fine Gold Particles from Philippine Gold Deposits by Enhanced Gravity Concentration and Flotation The objective of the study is to determine the applicability of enhanced gravity concentration (EGC) and flotation for gold recovery. While gravity concentration methods have long been applied to gold ores, especially to free-milling types that requires minimal beneficiation, flotation for gold recovery has not yet taken hold as a major operation in the Philippine setting. In this study, the application of EGC and flotation for gold is applied and compared to the existing methods for gold recovery. Two samples, with assays of 7.315 and 5.333 g Au/MT (samples 1 and 2, respectively) are used for this study. These samples are subjected to mineralogical studies and is found to have a gold-particle size ranging 10 to 200 microns. To verify the separation size, the mesh-of-grind (MOG) is used as the primary parameter for experimentation. Initially, the samples are stage-crushed, ground, and subjected to EGC using a Falcon SB40 Concentrator. Based on the results, the two samples showed that recovery increases with a finer MOG. The ratio of concentration (K) decreases with a finer MOG. This shows that there should be sufficient liberation of the gold values for EGC to be effective. The effect of the enhancement is to pronounce the difference in specific gravity of the minerals, promoting better separation. This is validated by the high recovery values of 86.97 per cent and 98.73 per cent exhibited respectively for samples 1 and 2 (at 54 microns). For the flotation runs, sample 2 with an average particle size of 80 per cent passing 74 microns is examined using thiocarbamate-based collectors for roughing and subsequently exhibited a recovery of 96.32 per cent. At this point, the concentration ratio (K) is noted as an important efficiency indicator for flotation process since it yielded a very low-mass and high-metal content concentrate.

Sep 13, 2010

By C Maloloy-on, S Morgan, M Deiparine, H Mackie

There is a strong focus in the mining industry to limit its impact on water quality and usage. This is even more evident in developing countries, where mining companies operate within local communities and have to be diligent not to affect them negatively. In mineral processing operations, the vast majority of water reclamation occurs at the tailings thickener area and tailings storage dam. It is often more effective to maximise water recovery at the tailings thickener before material transport to the tailings dam. Tailing dams are relatively inefficient, and experience a high degree of water loss due to evaporation, seepage and water retention. In addition, tailings dams present the biggest environmental liability for mineral resource projects, so it is beneficial to limit their size and loading.In the past, it was common for tailings thickener areas to have a significant footprint with several large diameter conventional thickeners, producing underflows of between 45-55% solids (w/w). At times, these multiple thickeners were difficult to operate, leading to inefficiencies in water recovery and quality. The development of High-Rate Thickeners (HRT) has resulted in improved settling properties and HRTs usually operate at significantly higher solids loadings (= 1.2 t/m2.h) when compared to conventional thickeners (= 0.1 t/m2.h). Subsequently, thickener diameters have reduced in size and HRT technology has become the preferred option for thickener circuit design in both new and existing operations. HRTs also produce higher water recoveries with increased underflow densities = 55% solids (w/w).The Carmen Copper Corporation (“Carmen Copper”) circuit upgrade is a recent example of these HRT benefits, where one, 39 m diameter, Outotec HRT treats the solids flow rate of five 76 m diameter conventional thickeners. This has allowed operations to increase dry plant tonnage by 50%, maintain key performance targets and provide a framework for further plant expansion. This paper details the sustainable approach to the Carmen Copper tailings thickener upgrade, where metallurgical performance, cost-effectiveness and environmental impact were key considerations.CITATION:Morgan, S, Mackie, H, Maloloy-on, C and Deiparine, M, 2015. Carmen Copper – a sustainable approach to tailings thickener upgrades, in Proceedings MetPlant 2015, pp 416–430 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 7, 2015

By Alvin J. F

Tin in ores containing 0·025 to 1·5 per cent tin can be determined polarographically by the reduction of the chlorostannite ion at the dropping mercury electrode in 2M hydrochloric acid solution containing 15 per cent ammonium chloride. The tin is separated from interfering elements by distillation as the tetrabromide and collected from the distillate by co-precipitation with aluminium hydroxide. The method can detect 0·01 per cent tin in ore.INTRODUCTIONAn iodimetric method, suitable for routine analysis of titrating tin in concentrations down to 1 per cent, has been available for some years (Low, Weinig, and Schoder, 1939).As concentrations fall below 1 per cent tin, there is increasing difficulty in obtaining a distinct end point due to large amounts of iron and silica normally present after fusion of the ore. Since concentrations of tin down to 0·02 per cent are significant in ore dressing products it was necessary to examine methods to determine such low concentrations, and to adapt these to tin ores containing a wide variety of other minerals.EXPERIMENTALDigestion and separationCassiterite, the principal tin mineral, is refractory but readily attacked by a sodium peroxide flux to yield soluble sodium stannate. In a recognized procedure, a sample of ore is mixed with up to 15 g of sodium peroxide in an iron crucible and swirled over the full heat of a Meker burner for 7 min. The fusion is leached with water and acidified.This solution then contains tin, silica, and other soluble...

Jan 1, 1962

By T P. Fischer, S N. Williams, N C. Sturchio

Chemical and isotopic analyses of fumarole gases from Galeras Volcano, Colombia provide significant insights into the origin of volatile components in the magma. Water comprises a mixture of magmatic (rock-equilibrated at high temperature) and meteoric, with the relative proportions varying through time. Carbon isotopes are most consistent with a mantle source, although other contributions to the system cannot be ruled out. Nitrogen most likely originated from organic matter in subducted oceanic sediments. All of these 'primary' components have been modified somewhat by interaction or exchange with other reservoirs during ascent to the surface. In addition to information on the origin of the gases, these data show significant temporal variations precursory to eruptive events. Chemical ratios change and water becomes more meteoric in character prior to eruptions.

Jan 1, 1995

OneSteel and BlueScope Steel have been working with the CSIRO to develop sustainable carbon fuels and reductants which are suitable for use in the iron and steel industry. One of the initial focuses of this work has been a process called steel recarburisation which is the addition of carbon to liquid steel to produce particular steel grades. This paper reports on the preliminary work and the recent full scale recarburisation plant trials conducted at the OneSteel Sydney Steel Mill.   Preliminary experimental work involved kilogram scale recarburisation of liquid steel with a range of commercial and prepared charcoal products. This work showed that charcoal dissolves into liquid steel very quickly and that carbon recovery to steel was inversely related to the charcoal volatile content. Initial larger scale work focused on the collection of wood, and preparation of low volatile charcoal which is required for steel recarburisation. Approximately three tonnes of charcoal was prepared at the Corrimal coke ovens of the Illawarra Coke Company. This charcoal was dried, crushed, sized and packaged in a form suitable for addition to 80 tonne liquid steel ladles.   The recarburisation trial was conducted over 30 ladle heats during June 2009. The charcoal was manually added to the liquid steel in 5 kg bags using normal plant practice. Conventional commercial recarburiser was also added to the liquid steel in alternate ladle heats. The performance of the charcoal was compared with the conventional recarburiser based on the carbon recovery to steel, hydrogen pick-up by steel and the rate of carbon dissolution into steel.   An analysis of the trial results showed that the charcoal performed at least as well as commercial recarburiser in carbon recovery and rate of dissolution but may have resulted in a slightly higher hydrogen content of steel. This is probably due to the higher moisture content of charcoal. The main challenges in the future include: increasing the charcoal density to improve transport and handling economics, securing a sustainable supply of biomass for the steel industry and developing a charcoal production industry so materials of suitable quality for both production and trials on other applications can be conducted.

Jun 1, 2010

The Hyde-Macraes Shear Zone (HMSZ) is low angle, duplex thrust system that has developed in a graphitic pelite schist within the Otago schist belt, New Zealand . At Round Hill lateral ramps have developed parallel to the movement direction between+ the footwall and hangingwall shears. These structures exhibit normal oblique-slip displacement which has been an important mechanism for creating space in an otherwise compressional system. Gold-bearing quartz veins were emplaced along the boundary shears and lateral ramps during thrusting. Gold within the lateral ramps is coarse (up to 300 microns) however hanging wall cataclasite development in the boundary shears after the gold was deposited has reduced the grainzise of most of the gold to less than one micron. This bimodal gold distribution has metallurgical implications with respect to the maximisation of gold recovery at Macraes.

Jan 1, 1993

By B A. Mowat, T M. Leach

The Morobe Goldfield inPapua New Guinea has produced in excess of 120 tonnes of gold from predominantly alluvial sources. Hardrock gold has been mined historically at Wau (23 t) and Edie Creek (4 t) and geological resources have been established at Hidden Valley (78 t), Kerimenge (36 t) and Hamata (30 t).Numerous prospects have also been identified within the goldfield. Primary gold mineralisation is related to intrusion of dacitic to andesitic Edie Porphyry (2.4 to 3.8 Ma), often with associated diatremes, which have intruded along major regional structures. A full spectrum of deposit styles from proximal (mesothermal) to distal (epithermal) to the porphyry source is recognised. The transition between the proximal and distal styles is recognised both between deposits and within an individual deposit. The deposit styles should be termed porphyry related gold mineralisation rather than given the generic epithermal and mesothermal labels.   It is proposed that magmatic fluids which evolved from parent melts to the high level Edie porphyry stocks mixed with convecting meteoric fluids and were channelled along major structure and diatreme contacts. Proximal to the intrusives, gold mineralisation is associated with deposition of pyrite-hematite-quartz+/-magnetite-gold (Hamata) and pyritebasemetals-quartz-gold (Wau). The mineralising fluids were hot, and periodically saline due to pulses of magmatic fluid. Gold is non-refractory and occurs as 20 to 30 micron blebs within the pyrite.   More distal from the intrusives or under late cooler conditions, mixing of cool dilute meteoric and magmatic fluids resulted in gold deposition associated with arsenic rich pyrite-and arsenopyrite-mineralisation (Kerimenge, Hamata and Edie Creek). Gold is refractory and occurs within the sulfides either as sub-micron inclusion or within the lattice.   CO2 and H2S gases which evolved off the upwelling hydrothermal fluids as a result of boiling and pressure reductions, condensed within superficial groundwater and formed cool oxygenated bicarbonate fluids. These fluids percolated back down the structures depositing manganocarbonate in the upper parts of the hydrothermal system. At deeper levels in the system mixing of the descending bicarbonate fluid with upwelling mineralised fluids deposited manganocarbonate-quartz-sulfides nonrefractory gold (Hidden Valley, Wau and Edie Creek).   At Kerimenge the cool bicarbonate fluids have also quenched a late stage magmatic fluid rising along high permeability structures. The quenching has resulted in deposition of non-refractory gold mineralisation associated with hessite (Ag2Te)-tennantite-chalcopyrite deposition.   Within the Morobe Goldfield, a transition from deeper level pyrite-quartz+/-hematite-magnetite to intermediate level quartz sulfide and quartz-carbonate-sulfide deposition to upper level, massive manganocarbonate deposition is recognized. Gold mineralisation can occur within all levels up the system.

Jan 1, 1995

At Great Boulder Gold Mines Ltd. a number of attempts were made to remove water soluble copper and iron salts from calcined pyritic concentrates but variou~ problems arose and the methods were abandoned.A method of rapid washing has been developed and although some problems still exist a workable process was established which resulted in substantial savings of reagents used for the cyanidation of calcine.INTRODUCTIONIn the Great Boulder flowsheet crude ore is ground in cyanide solution, then thickened, agitated and subjected to two stage filtering. Secondary filter discharge is pulped with flotation circuit water, gassed with sulphur dioxide to precipitate soluble gold and activate pyrite, and after the addition of copper sulphate and xanthate, the pyrite and tellurides are recovered by flotation. Flotation tailings are thickened and pumped to the disposal area and concentrates are calcined in Edwards roasters. Calcine is washed to remove water soluble copper and iron salts and the washings pumped to the flotation section where the copper is used as an activator. The washed calcine is cyanided and returned to the crude ore circuit via the thickeners. Solution for precipitation in the Merrill Crowe is drawn from the crude ore thickeners.Prior to the introduction of calcine washing the calcine contained 7 lb/ton copper of which approximately 60 per cent was water soluble. It also contained approximately 90 lb/tol'l of water soluble iron salts. Both the copper and...

Jan 1, 1964

The consideration of environmental constraints and issues is a fundamental component of all stages of planning, development, operation and decommissioning mining and quarrying projects. Provision needs to be made at all stages for the cost of environmental components since it is of fundamental importance that they be recognised as an integral component of any project. This paper presents an approach to environmental costing, suggested levels for budgeting, and the cost benefits.

Jan 1, 1990

Remote sensing, in general, is the recording of light and heat from a planet's surface within a certain range of the electromagnetic spectrum. For the Earth, systems capable of this recording are the MultiSpectral Scanner (MSS) and SLAR. The former is the recording system used in satellite and will be discussed in the next section. SLAR stands for Side Looking Airborne Radar. This device sends invisible radar waves which illuminate the Earth's surface. The reflected waves are subsequently recorded as images. The system can operate through darkness and dense cloud cover, and is particularly suited for the study of geological structures at both large and small scale (Wayland 1976). Remote sensing techniques are now widely being made use of in mineral exploration, especially for those last remote 'sanctuaries' where geological data are meagre or non-existent. For places like Borneo, West Irian, the Amazon Basin etc. remote sensing, in the form of both satellite imagery and SLAR, is of considerable help, in fact more often than not the only help, to delineate geological provinces, geotectonic domains and meaningful lineaments. In the case of New Zealand, well made geological maps at scale 1:250 000 by the Geological Survey are available to the public and these provide useful preliminary grounds for the selection of target areas. However, even in this case LANDSAT imagery can be of aid as will be shown later.

Jan 1, 1977

Entry of personnel under a vertical raise bored hole is not standard practice in Australia. Where access is required below a rise, mining operations must be confident that they understand the capacity of the ground control specified and installed. Physical modelling was conducted on Callie mine to evaluate the performance of 5 mm steel wire weldmesh secured to the base of a vertical raise bored hole of 1.4 m diameter. Joint orientation data was used with Unwedge to calculate a series of potential wedges likely to form within the rise. The mass of the most likely wedges were then replicated by collecting rocks in 5 kg increments (¦10 per cent), which were allowed to freefall onto installed mesh at the base of a 40 m vertical rise. The results indicate that two sheets of mesh can retain a freefalling rock of at least 20 kg mass although rupture of strands can result. This paper outlines the test conditions, expected results based on theoretical calculations and actual outcomes of the testing.

Nov 25, 2010

By C Li, D O’Dea, R Moreno-Atanasio, T Honeyands

The behaviour of iron ore granules in the feeding process of sintering is significantly influenced by the material properties of the granulated mix. Therefore, the measurement of key material properties of the iron ore granulated mix is indispensable prior to the simulation of the sintering process based on the discrete element method (DEM). In this paper, three key property parameters of the iron ore granulated mix, apparent density, elastic modulus and rolling friction coefficient, were measured in laboratory-scale experiments. For different sintering processes, the moisture content of the granulated mix normally varies according to the specific requirements for granule size distribution and operating conditions. Therefore, understanding the effect of moisture content on the property parameters of iron ore granules is very helpful in accurately determining the property parameters for DEM simulation work. In this paper, six groups of iron ore granule samples with six levels of moisture contents were prepared through granulation and the trends in apparent density, elastic modulus and rolling friction coefficient with the increase of moisture content were plotted and analysed based on the measurement results. The results show that as moisture increases from 6.9 per cent to 9.1 per cent, the apparent density decreases from about 3000 to 2800 kg/m3. With moisture increasing within the same range, the elastic modulus first decreases from over 200 MPa to below 100 MPa and then reaches a relative constant value of about 40 MPa at higher moisture contents. Rolling friction coefficients are measured using two methods with both indicating a similar trend, with the rolling friction coefficient first decreasing and then rising as moisture increases from 6.9 per cent to 9.1 per cent. The relationship between µr and µ’r is assumed to be similar to that between static and dynamic friction coefficients.CITATION:Li, C, Moreno-Atanasio, R, O’Dea, D and Honeyands, T, 2017. Variation in property parameters of iron ore granulated mix with moisture content, in Proceedings Iron Ore 2017, pp 79–84 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 24, 2017

Every automatic citizen is an automatic recipient of a miner's right under the present Mining Act (Chapter 195), but this alone does not entitle any automatic citizen to mine for minerals on any land, even his customary group's land. Without complying with requirements of the Mining Act, any automatic citizen who engages in mining solely on the basis of a miner's right would be mining illegally. He would also be engaged in illegal mining if he mines on customary or other non-government land. Even if mining is legally pursued by an automatic citizen, he does not acquire ownership of minerals without first making the required royalty payments to the State.

Jan 1, 1991

By G Tripp, G Lorusso

The Velvet gold orebody (153 Koz Au) is located near the Kanowna Belle gold deposit in the Boorara Domain of the Kalgoorlie Terrane, a subdivision of the Archaean Eastern Goldfields Superterrane (Swager et al, 1990). Gold mineralisation at Velvet is hosted within an intrusion of intermediate composition that broadly follows a sub vertical hanging wall splay of the Fitzroy Shear Zone.Velvet was discovered in 2003 during an underground exploration drilling program targeting potential strike extensions to the Kanowna Belle deposit. Diamond drill hole KDU1595 returned a downhole intercept of 36 m grading 4.6 ppm Au approximately 500 m west of the deposit and at a vertical depth of 700 m below surface in the immediate hanging wall of the primary Kanowna Belle host structure, the Fitzroy Shear Zone. Subsequent drilling completed following the initial discovery, from both surface and underground collar positions, failed to replicate this result.In 2014, KDU1595 was resurveyed gyroscopically and the mineralised intercept correctly located. Additional drilling was undertaken to follow-up the repositioned discovery hole. Challenges included poor drilling angles through the Fitzroy Shear Zone, excessive deviation during drilling and the unknown geometry of the target. Navigational drilling helped to successfully penetrate the Fitzroy Shear Zone and in April 2015, drill hole KDU3234 returned a significant downhole intercept of 45 m grading 5.6 ppm Au.Additional drilling success resulted in a decision to develop a 600 m drive to serve as a dual-purpose access for further exploration and mining. This was a potential risk considering that the orebody geometry was unknown and all significant drilling results were clustered within a 50 m × 50 m panel. Development commenced in June 2015 and the first ore cut taken in April 2016. Geological mapping and structural interpretation, together with multi-element and spectral analysis of drill samples has enabled several other target areas to be identified for exploration. The Velvet mining area is critical to continued production at Kanowna Belle. Geological understanding must advance as mining progresses to ensure continued resource growth and optimal extraction of reserves.CITATION:Lorusso, G, Rogers, J and Tripp, G, 2017. Velvet underground exhumed – discovery and development of a new mining front at the Kanowna Belle gold mine, in Proceedings Tenth International Mining Geology Conference 2017, pp 169–174 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 20, 2017

Detailed characteristics of gold from Pliocene auriferous quartz gravels from Waimumu (Southland) have been studied using a combination of optical microscopy, energy dispersive microprobe analysis and scanning electron microscopy techniques. The gold at Waimumu is classified as either: 1. detrital gold, or 2. irregular gold. A number of different morphologies a recognisable within each 'gold type'. Evidence is given for an predominently authigenic origin for some of the gold at Waimumu.

Jan 1, 1987

A description is given of preliminary work done to identify the problems inherent in electrochemical oxidation of metal sulphides, and particularly in the use of powder compacts as anodes in electrolysis. Lead flotation concentrate pressed into a compact can serve as an anode for direct electrowinning of lead according to the reaction PbS -7 Pb2+ +So +2e. No pYrometallurgical step is required, and sulphur is recovered in elemental form.In the experimental work, electrical conductivity of the compacts was achieved by addition of 5·5 per cent of graphite. After compaction at 10-20 tons/sq. in. the anodes were strong and remained intact throughout the electro-oxidation period. Perchlorate electrolyte was used, but fluosilicate electrolyte is also applicable. A sheet of pure lead formed the starting cathode.As anode potential increased above 1·0 V (v. SHE) PbS04 was formed in increasing amount. At 0·90 V, Pb2+ extraction efficiency was 85 per cent. Anode potential was kept low by electrolysing at 60°C and 15 mA/sq. cm., and by improving the porosity of the compact. Other metal sulphides (Zn, Fe, Cu) in the flotation concentrate also oxidize and release metal ions to the electrolyte, which would need to be purified prior to deposition of lead.Power requirement in a laboratory cell was about 0·24 kWh per lb of lead extracted.

Jan 1, 1972

The term slag has been used to define a wide variety of material including mine spoil and slag produced at steel plants. The present paper is concerned only with the non-metallic alumino-silicates developed simultaneously with iron in blast furnaces.The control of iron quality by slag has long been appreciated but here aspects of slag control based on concurrent iron production are indicated. Consideration is given to the basic composition of slags relative to the type of allotrope required. Up to a point, the plant conditions, under which a particular slag type is processed, have some effect, but these conditions only widen the range of a given allotrope.They do not convert one slag type into another. The nature of the slag types and experiments with additives to convert one slag type into another are discussed.The various uses for allotropes of blast furnace slag are considered.Their use in air cooled slag, foamed slag, slag wool, cements, soil stabilization, glass bottles, and building bricks and blocks, is explored in some detail.INTRODUCTIONWithin recent memory, blast furnace practice has been solely concerned with the production of iron. The slag make at this time had not reached embarrassing proportions. In Britain, unlike Germany, no legislation existed to prevent the growth of unsightly slag banks. Generally slag found limited use as fill and road material in the immediate plant vicinity. This is broadly the case in Australia today. In Europe and America, where the slag make is of the order of several million tons annually, the room problem and the cost of dumping slag has stimulated commercial and scientific research on the disposal problem. Currently, most iron plants in Europe can profitably dispose of at least 95 per cent of their slag make.

Jan 1, 1964