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By Lawson F

Narrowly sized samples of synthetic chalcocite (Cu2S) and covellite (CuS) were leached in oxygenated acidic sulphate-chloride solutions. Chalcocite leaches via a two-stage process, the first stage being much more rapid than the second. The apparent activation energies are 42.7 kJ/mol and 68.2 kJ/mol respectively, indicating that both stages are controlled by surface chemical reactions. The leaching of covellite is also chemically rate limited with an apparent activation energy of 77.0 kJ/mol. The shrinking core model is able to be used to describe the leaching processes of both copper sulphides. Over 97% of copper present in chalcocite dissolved in 0.5 M H2SO4i0.5 M NaCl solution under one atmosphere pressure of oxygen at 85¦C in three hours from particles 36 pm in diameter while only 85% of the contained copper in covellite particles 13 pm in diameter dissolved in the same solution under the same pressure at 90¦C in six hours. About 99% of the sulphide sulphur in chalcocite was oxidised to elemental sulphur while only 90% of sulphide sulphur was converted to elemental sulphur during covellite leaching. The mechanism proposed for the two-stage leaching of chalcocite particles is as follows: in the first stage, cuprous ions rapidly diffuse to the external reaction surface where they lose electrons and go into solution as a complex cupric chloride ion CuCl'. The second leaching stage begins when covellite is formed at the external surface. Copper again goes into solution as the CuCl* ion. The mechanism for leaching synthetic covellite is similar to the second leaching stage for chalcocite except that the leaching rate of synthetic covellite is substantially lower than that of the newly formed 'covellite'. Elemental sulphur formed on the particle surface retards the dissolution processes during both chalcocite and covellite leaching. The presence of chloride ions is necessary if essentially all of the copper from chalcocite is to go into solution. When no chloride ions were present, the leaching rate of both newly formed and synthetic covellite was almost zero. The main role of chloride ions in both chalcocite and covellite leaching appears to be to disrupt the passivation film of sulphur on the particle surface.

Jan 1, 1989

By Jowett A

To compare open circuit lead primary rougher results at Mount Isa Mines Ltd., eleven surveys were made over five weeks of plant operation with varying ore sources, including a specially hauled sample of 100% Black Star ore. Three of the surveys which represented extremes in performance were selected for sizing, cyclosizing and assaying for lead, zinc and iron. A comparison of the flotation kinetics has revealed the similarities (including common problems) and differences for the surveyed ores. The concepts of entrainment and collectorless flotability are used to aid interpretation of the kinetic data.

Jan 1, 1978

By Golab K, Partridge AC, Fletcher CAJ, Holtham P

Spiral concentrators are used globally in the fine coal processing industry to segregate particles, by gravitation, on the basis of density and size. Consisting of an open trough that twists vertically downwards about a central axis, a slurry mix of particles and water is fed to the top of the concentrator. Particles are then separated radially as they gravitate downward. Since their introduction to Australia in the 1940's, the generic design has evolved largely by laboratory trial-and-error investigations of different prototypes. However, this approach has proven expensive and optimal designs have not been necessarily developed. Accordingly, Computational Fluid Dynamics (CFD) analysis has been used recently as an alternative method of investigation, to assume as is envisaged, a role in the design process. To date, CFD models have progressed to simulations of turbulent fluid flow on current production spiral designs, and are continuing to be adapted for inclusion of particles at realistic feed concentrations. To be able to use the models confidently however, laboratory experiments must also be performed to validate the predictions during the development stage. This paper reports the current findings of an ongoing CFD and experimental program applied to one spiral unit. Satisfactory quantitative agreement has been achieved for the fluid and particulate flow characteristics, and although further validations are appropriate, the model already possesses significant potential for use as a reliable predictive design tool.

Jan 1, 1998

The excavation of sandstone of generally medium strength for the Liverpool Link Line by Dosco Mark 2A Roadheaders has demonstrated the versatility and good performance of road- headers in suitable rock formations. A description is given of the strata traversed by the tunnels together with descriptions of equipment and crews, excavation sequences, operating difficulties and the results achiev- ed. In addition tunnel construction is des- cribed for a difficult section where there was only O.Sm clearance between invert and a four lane vehicular tunnel below, and O.5m clearance between tunnel crown and a century old sewer above.

Jan 1, 1976

By Szymanski J, Planeta S

For many hard rock mines with near surface deposits, the surface crown pillars form the first line of protection for the immediate underground workings. Underground stopes are typically contained by crown pillar, which protects the level above, rib pillars, and a sill pillar through which the ore collection system is cut. This paper discusses the mining of these pillars, with particular emphasis on the overall stability of the mined out upper part of the mine areas. An area of interest is located in the Canadian Shield, where the mining has progressed below four thousand foot level in the ultramafic high grade sulphide type of orebody.

Jan 1, 1995

By Distin P. A

The extraction of platinum and rhodium from scrapped honeycomb autocatalyst into hydrochloric acid/aluminum chloride/nitric acid solutions is described. Results are given for the effects of leachant composition, temperature and catalyst pre-reduction using hydrogen. Data are also presented for the recovery, by hydrogen reduction, of platinum and rhodium dissolved in the leach solution. Parameters studied include solution composition and temperature, hydrogen pressure, and platinum seed addition.

Jan 1, 1992

The Rock Mass Rating (RMR) and Rock Mass Strength (RMS) classification systems for jointed rock masses are briefly reviewed, with particular reference to their use in slope stability studies. A correlation is provided between the results obtained from the two classifications and an equation is presented tentatively defining the RMR value for long-term stable slope angles. The validity of the equation is discussed in general terms in the context of slope stability problems commonly encountered in Western Australian open pit gold mines.

Jan 1, 1992

By McAuley T. J

Computer software is an integral part of mining operations today with many sites using six or more software packages on a daily basis. However, the use of these different programs generates the need for substantial staff training. The current trend toward large integrated packages to solve this problem is counter-productive because the relatively small companies producing specialised mining software do not have the resources to develop quality software with all the required features. Software standards are being proposed by various parties but recent history indicates these will be unsuccessful. An alternative approach is suggested using the various standards which have been developed for the Windows operating system.

Jan 1, 1995

By Colston M. B, Johnson I. D

The importance which matters of social welfare and environmental quality have assumed recently is the underlying theme of this paper. Demands for infrastructure reflect the change in emphasis from economic and technological development to those issues which affect the total well-being of the community. To put the importance of social change in perspective, examples are cited and a theme is developed which underlines the relevance of changes in public attitude and in government policies on mineral exploitation and related development and on the regimen of associated infrastructure sought. Planning on a long term or strategic basis and on a broad scale is put forward as an effective means of identifying changing social attitudes for the purpose of framing government and corporate policies. As a prelude to a section in which a description is given of a novel 'services baseline' concept and its use in the assessment of the current backlog of services

Jan 1, 1977

The evolution of Hall process alumina reduction technology is des- cribed with particular attention to the pot lines. Future directions of tech- nological change are considered. It is predicted that the Hall process will continue to be the avenue for aluminium production for some time to come.

Jan 1, 1982

Alcoa of Australia's Del Park mining op eration is centred 9 km. east of the Pinjarra alumina refinery, and is centrally locatedwith- in the 10, 000 sq. km. lease which the Company holds for bauxite in the Darling Ranges. An- other mining operation is situated near the township of Jarrahdale, and supplies bauxite to the Kwinana refinery. Definition of the bauxite ore, development works and mining to the ore haulage stage, are identical for both mining operations. Exper- ience, and production cost figures, obtained from the Jarrahdale mine, where 100 tonne trucks are used to haul ore to a fixed crushing plant, led to the development of the Del Park mining concept with increased mobility of op- erations. The crushing-conveying-stockpiling arrangement at Del Park consists of a 1200 t. p. h. mobile crusher feeding bauxite to an overland conveyor system which transports the ore approximately 6. 66 km. to the stockpile area in the refinery. In the refinery raw mat- erials area the bauxite is distributed into 200, 000 tonne stockpiles by means of a travel- ling boom stacker.

Jan 1, 1973

By Fuller P. G, Dugan K. J

Artificial support can be used to improve wall stability in open pit mines. This is examined for a particular case where the factor of safety for a slope is kept constant by using artificial support as the slope angle is increased. It is demonstrated that the savings in excavation generally exceed the cost of support. However, in order to correctly judge the eco- nomic impact of artificial support on the project, all the elements relat- ing to the use of artificial support must be taken in account.

Jan 1, 1989

Data logged on mineral beneficiation processes during normal operation are analysed using time series (correlation and spectral) methods to identify the dynamics of the processes for on-line computer control. Recursive least squares estimation techniques are used to identify parametric models for a cassiterite flotation circuit and a coal washery. Identification problems such as the determination of model order, process time delays and the 'contamination' of the data by process recycle streams (feedback) are discussed. Typical results are presented in which optimised models are identified from data logged during normal operation.

Jan 1, 1985

Comminution Kinetics equations are developed to take into account difference of grindability of mineral components. The equations describing both batch and closed circuit grinding or crushing processes are given. These equations are applied to industrial data to derive comminution kinetic and classification characteristics of the component minerals in a multi-mineral ore. Control strategy based on these concepts is presented.

Jan 1, 1985

It is a privilege for me to participate in this vitally important discussion of The Role of Governments in the Management of Resources. The distinction of my fellow participants is evidence that this event is a matter of extreme importance and attracts international attention. In the management of natural resources, government and private enterprise share awesome responsibilities for the economic well-being of nations. Mining and its relation to the prosperity of nations is almost as old as recorded history. Copper was being mined and extractive metal- lurgy practised at Timna in Israel's southern desert as far back as 4000 B.C., and the rich mines of Laurium not only saved the Greeks from Persian domination 2500 years ago, but also provided Athens with a monopoly of silver in the Mediterranean world. This bolstered the economic power of Athens and led to the golden age of Greek commerce and culture.

Jan 1, 1978

By Dyson NF

Nickel sulphide precipitated from waste liquors at the Yabulu plant of Queensland Nickel Pty Ltd was pressure leached under various conditions. Leaching at 130¦C and 700 kPa of air dissolved 95 per cent of the nickel as the sulphate in less than 2 h. Leaching at 130¦C and 350 kPa of oxygen dis- solved 95 per cent of the nickel in less than 1 h. Dissolution was faster with oxygen than with the equivalent pressure of air. Crystallization of hydrated nickel sul- phate from the resulting clarified leachate is readily achieved. Because the sulphide pre- cipitate also contains minor amounts of iron, copper and cobalt, the crystallization product contains these metals in excess of the amounts required for electrolytic-grade nickel sul- phate. This grade of product could only be produced if the contaminants were removed prior to crystallization. Alternatively, the "crude" nickel sulphate could find a market as a feed for the electrolytic production of Ni-Fe coatings.

Jan 1, 1984

This paper reviews hydrometallurgical processing technology for refractory gold ores, which form an increasing resource stock for gold. The reasons fQr ore refractoriness and pressure, chemical and biooxidation process options are briefly listed. Electrochemical technology, suitable for processing refractory ore is reviewed and some preliminary results for the electrochemical oxidation of slurried arsenopyrite are given.

Jan 1, 1992

By T E. Norgate

Salinity in Australia is caused by over irrigation and land clearing for agricultural use over the last 100 years. It is now the biggest threat to the quality of land and water in the Murray Darling Basin and Western Australia. Pumping the saline waters straight into the ocean or transporting the solid residue (mainly sodium chloride) to the ocean after evaporation of the water is expected to cost the taxpayer millions of dollars every year. This paper proposes that the salinity problem of Australia, at least in part, can be converted to an asset rather than a liability if it is exploited and used to make value-added products. The more value made out of saline waters, the more saline water is processed and therefore the more salt is extracted from the land. The value-added products that can be made out of saline waters are numerous and diverse. Rough calculations show that value addition to the saline waters could potentially generate up to $A 200 million per annum business in the Murray-Darling Basin. Although it is a challenge to make cost competitive products and find markets for these products it is possible that up to $A 100 million per year may be gained from import substitution. Value addition to salinity would also reduce the threat on the environment and existing agricultural industry. Investment to add value to salinity will create business in the region, nurture the local small population communities, and increase services and long-term employment.

Jan 1, 2002

By Bratt G. C, Horsham T. R, Langlois D. R

Mercury is precipitated from weakly acidic sulphuric acid plant waste liquor at the Risdon Works of the Electrolytic Zinc Company of Australasia Limited. Factors determining the choice of process and reagent, as well as details of process development including scale- up, and the time scale of implementation are outlined. The plant is designed for a maximum flow of 120 m3/h.of liquor containing mercury and saturated with sulphur dioxide. Mercury is precipitated by fluidised beds of aluminium pellets contained in lead columns. Liquor is then clarified with plate and frame presses. Experimental work on the mercury precip- itation reaction was conducted in three phases involving a scale-up of 100 times in equipment size. Extensive pilot filtration work was carried out on a 1 m2 press. Scale-up of 120 times was required for specification of plant filters. The basis of scale-up is outlined.

Jan 1, 1977

By Morris B. J

Soil air samples taken from the top one metre of the soil profile, were measured for C02 and 02 using portable field analysers at a number of sites of known sulphide mineralisation in South Australia. Carbon dioxide anomalies were detected over actively oxidising sulphides during autumn and winter following recent rainfall. Anomalies were not detected where no oxidation was occurring, where seasonal conditions had been very dry, or where the sulphur content of the ore was low (

Jan 1, 1993