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The interaction of flotation collectors with sulphide minerals takes place at the solid - solution interface. The electrochemistry of the processes which affect this interface are discussed. The interaction of xanthates with sulphides is an electrochemical process, xanthates being electro-oxidized to chemisorbed xanthate and dixanthogen. The role of oxygen is to provide a cathodic process to allow the anodic oxidation to occur. The hydrophobic condition of the mineral surface is brought about by the presence of the oxidized xanthate species. The action of reagents which can activate or depress the flotation of sulphides is discussed briefly.

Jan 1, 1980

The article presents methods of testing and recording of water amount pumped out in surface mining. The authors describe necessary recommendations how to carry out measurements so that one can separate the surface run-off and groundwater inflow from the total inflow. They demonstrate methods of evaluation of these kinds of inflow in open pits when water amount testing is carried out every eight and 24 hours as well as simple methods when only monthly records of water are available. The authors also describe procedures for evaluating the water inflow when an open pit is dewatered gravitationally and measurements in discharge channels are irregularly carried out.

Jan 1, 2003

By Maru Y

The use of mercury for amalgamation has been an integral part of the small-scale gold mining industry in developing countries owing to its low investment cost, simplicity of the technique and high gold recovery. However, its impact on health and environmental hazards have not been given the attention they deserve. In spite of the growing awareness and concerns over the mercury pollution problem by regul-atory authorities, precautionary measures such as bans on the use of mercury in some countries have been largely ineffective.This paper first reviews some of the mechanisms of mercury poll-ution, and mercury toxicity which varies according to its oxidation state. It then describes how mercury released to the atmosphere would go through the "Mercury Cycle". Compar-isons have also been made with previously measured mercury levels in small scale Papua New Guinean miners with their counterparts in other developing countries.

Jan 1, 1994

By Huajun W, Long LZ

The composition of fly ash and formation mechanism of cennospheres are introduced in this paper. The signification of using this potential new mineral processing resource is emphasised. The beneficiation properties of the components of fly ash, such as susceptibility, specific gravity, size, shape and flotability etc have been examined in detail. A technique was designed to process fly ash from the XiGaoJing power plant in Beijing, and a flowsheet is also presented. Flotabld cennospheres, magnetic beads, sinkable beads, carbon and advanced pozzolamics can be obtained as separate products through this flowsheet. It is emphasised that the beneficiation of fly ash is an efficient means of totally utilising the resource. Examination of the products show that they have good physico-chemical properties. Possible areas of their application are also Suggested.

Jan 1, 1993

Australia has been a major exporter of LPG since production from the Bass Strait fields commenced in 1970. Export levels have been maintained through the seventies, the bulk of material being delivered to Japan. During this period the use of LPG in domestic markets grew only'slowly and demand was largely met by production from refineries with only shortfall supplies being drawn from naturally occurring sources. The domestic demand is forecast to grow significantly during the eighties as the traditional, automotive and petrochemical uses of LPG are expanded. An increasing amount of naturally occurring production will be directed into these markets. Despite this redirection the current level of exports (about 1.5 million tonnes per year) is likely to be maintained through much of the decade ahead as production from the Cooper Basin and the North West Shelf becomes available.

Jan 1, 1982

Having successfully applied computer techniques to open pit mining applications, many software developers are now using their skills to tackle the much harder areas of underground mine design, planning and production.Dramatic improvements in the performance to price ratio of hardware (including high resolution graphics screens), a better understanding of the techniques of surface and solids modelling (and their subsequent display), moves towards standard user interfaces and advanced concepts of representing grade distribution in the ore body have all contributed to the recent increase in underground mining software activity.This paper details the general requirements of a workable underground mining software system, providing a minimum checklist of desirable features and emphasises the importance of ease of use, flexibility and intuitive feel. Some relevant trends in hardware, software and application techniques are highlighted and comments made on areas which require further development or are only available in a small number of packages.Finally, a comment is made on the role of computer models to provide a unifying medium for tying together all aspects of underground design, planning and production.

Jan 1, 1992

By W Lu, D Wang

Study of coal oxidation at low temperatures forms the basis of investigating the inherent properties of spontaneous combustion of coal. In general, the process of coal oxidation at low temperatures is very complex, involving many factors. Experiments examining the properties of oxidation and ignition of coal have been carried out. Based upon the results of these experiments, the catastrophe properties in the process of coal oxidation are analysed and the mechanism of catastrophe is proved for the ignition of coal. A folding catastrophe model is also established for the process of coal oxidation. Results obtained show that the process of coal oxidation to ignition is discontinuous, where the coal-environment system yields structure destabilisation. The system can jump from one stable attractor to another. The research results presented in this paper help to show the irregularities of coal oxidation at low temperatures and how to pursue effective control measures.

Jan 1, 2005

By Fuerstenau DW

The flotation of pyrite in ethyl xanthate solutions is presented along with electrokinetic results. The results have been analysed in view of recently published thermodynamic calculations as well as other published data on the pyrite-xanthate system including adsorption and voltarnmetry studies. The flotation response of pyrite in xanthate solutions is characterised by two maxima, one at pH 4 and the other at pH 8-9. The acidic maxima is also associated with a reversal in the electrophoretic mobility of pyrite, probably due to the formation of ferric xanthate on the pyrite surface through chemisorption of xanthate ions while the basic maxima is not associated with major changes in the mobility and flotation at this pH can probably be attributed the adsorption of dixanthogen. It is concluded that there is not sufficient experimental evidence to conclusively attribute the lack of flotation response in solutions at near neutral pH to any particular phenomena, either kinetic or thermodynamic.

Jan 1, 1993

As mines become deeper, the problems of heat in the workplacebecome more acute. An important response from the industry hasbeen the widespread adoption of microclimate cooling such asair-conditioned cabins. However, not all work in mines can becompleted from inside an air-conditioned cabin, and in any event,it is still important to keep the ambient air in the mine outside ofany microclimate to a safe temperature. An important method forbringing workplace temperatures under control is the appropriateuse of refrigeration. The application of refrigeration inmechanised mines has been recently described (Brake, 2001;Brake and Fulker, 2000). This paper provides an overview ofsome of the important engineering considerations in thespecification and selection of mine refrigeration plants. Thepurpose is to provide a basic understanding of refrigerationprinciples, practices, terminology, hazards and opportunities formining engineers or other personnel who may need to beinvolved in the introduction of refrigeration onto a mine site.

Jan 1, 2001

An intensely sheared and mineralisedIzone occurs in the Quartz Dolerite Greenstone (or Younger Greenstone) mass on, the western limb of the Kalgoorlie Syncline. This zone comprises the western part of the Golden Mile and has produced the greater part of the 33,000,000 ounces of gold produced to date from the main mining belts. A study of.th e general geological and structural features gives rise to the expectation that the lode shear system,will continue southward on a pitch similar to that of the maln syncline whose axial plane may be referred to as the "Boulder Dyke". Although payable ore has recently been found further south than previously, the expectation of large quantities extending southward from the present mining areas is Problematical.'

Jan 1, 1964

The Geograph is a revolutionary seismic system involving special techniques in combining the use of FIT magnetic tape with shock wave echoes created by a weight dropping system.The idea of- weight dropping as a- source of seismic energy is not a new,.,oxie. Records 'indicate òa pos'sihle use of falling weights as early as .1929. 'Dr. Burton McCollum began his experiments in 1938, but it wasn't until 1951 that the method was first proven useful.The first weight dropping crew began commercial operations in Edwards and Sutton .Counties of West Texas in 1953. By 1962, more than '40 weight drop-ping.crews have come into existence with operations in the United States, Canada, Algeria, Iraq, Argent na,òSpanish West Africa, Tunisia, Qatar, Niger Morocco and Libya by most major oil companies and larger independent oil companies. .

Jan 1, 1962

By B J. Fallon

This study used structural equation modelling (SEM) to develop a series of models to explain the impact of work-life balance on employeesÆ perceptions of job performance, job satisfaction, turnover intentions and absenteeism. The sample comprised 257 participants (108 males and 149 females) from a range of occupations and levels of seniority. In sum, the results clearly demonstrated that successful work-life balance is associated with higher levels of job performance and worker satisfaction and with decreased levels of absenteeism and turnover intentions. The data also lent support to the impact of employeesÆ coping styles, schedule flexibility and supervisor support on employeesÆ abilities to balance work and life. It is concluded that tangible benefits to an employerÆs bottom-line can be anticipated from organisational initiatives to assist employees to better balance their work and personal lives.

Jan 1, 2005

Differences in the assay results of replicate samples engender doubts on the reliability of ore sampling and of assaying procedures. An analysis of variance is a technique to estimate the variability at each level of the procedures. In an example, the variability of one-metre core samples was far greater than that of the assaying technique.

Jan 1, 1976

Efficient performance of pulp lifters to discharge ground rock is critical to the effective performance of SAG and AG mills. The paper covers developments in the design of pulp lifters and associated grates, of both conventional straight-radial and curved types, and of the inner discharge cone. Issues covered include the discharge performance of both the slurry and rock components of the discharge, reverse flow back into the mill through open grates and backflow down the pulp lifters of material that fails to discharge from the mill. The design experience is interpreted in the light of developments in particle flow modelling of the flow of charge in pulp lifters.

Jan 1, 2004

By Ruffles B. R

A computer simulation has been developed to model the flow of copper ore in Isa Mine. It simulates extraction of copper ore from the 1100 orebody by load-haul-dump (LHD) units to ore passes, haulage from chutes on 19 level by Rockflo trains to crusher bins, crushing and hoisting. It can assess in terms of the tonnage and head grade of ore hoisted, the effect of varying operating strategies, as well as measur- ing shortfalls in required capacities of any of the operations (extraction, hauling, crushing and hoisting). The simulation was designed as a modular, deterministic, steady-state model with parameter input allowing complete flexibility in its use. Queuing theory is used extensively to evaluate the effect of interference at potential bottlenecks. The model has been used to determine the effect on production of varying train sizes, maintenance policies on the haulage circuit, orepass capacities, and extraction operations.

Jan 1, 1974

The mineral sands industry in Australia can contribute much more sig- nificantly to economic development beyond the year 2000 by increased production of constituent minerals such as ilmenite, zircon, rutile, leu- coxene and monazite from existing and new resources, and especially from downstream processing to intermediate and finished products based on these resources. The end-use areas for mineral sand-based products include those products whose demand is tied to general economic growth, such as paints and plastics, and refractory bricks for the steel industry. High techno- logy applications such as zirconia ceramics and super-magnets are indica- tive of new developments in technology which provide considerable scope for expansion at higher rates than overall western world economic growth. An optimistic outlook for the industry is outlined, based upon a brief review of opportunities.

Jan 1, 1988

By Thorburn D

This paper reviews the history of environmental assessment in New Zealand with reference to mineral developments. Emphasis is given to larger more controversial projects particularly metal mines. The changing role and application of the Environmental Protection and Enhancement Procedures is examined in the context of changes in the government's environmental administration and the response of the Ministry of Energy's resource allocation group. Conclusions are drawn on the effectiveness of the present environmental assessment activities and on the allocation of administration of priorities in the Ministry. The Ministry of Energy has effectively ceased to exist.

Jan 1, 1990

By M H. Mian

Much has been published on resuspension of sediments in lakes and estuaries. In general, resuspension has implications on transport and release of contaminants from the sediments. It has been shown that wind-induced waves contribute to erosion of sediments, which are then distributed to various sections of the water body by currents. Empirical equations formulated on the basis of cohesionless sediment behaviour have been applied to the design of a few tailings ponds in different parts of the world, especially in the selection of the necessary depth of water to minimise negative environmental impacts. The paper highlights the shortcomings inherent in these equations using field-measured data from a tailings site in Canada. Laboratory measured tailings properties are used to identify critical shear stresses required to initiate tailings erosion. The influence of cohesion on resuspension of fine-textured tailings is discussed.

Jan 1, 2003

In the past two decades the global metalliferous mineral industry has trended away from pyrometallurgical (pyromet) and towards hydrometallurgical (hydromet) technologies including biometallurgical (biomet) processes. Pyromet, biomet and hydromet technologies have all developed considerably over this period. New projects have been biased or directed by legislation towards supposedly cleaner and greener hydromet and biomet technologies. The environmental cost and energy cost of pyromet production processes for copper and cobalt are compared with comparable hydromet processes using Life Cycle Assessment (LCA). The æreal costÆ of the global warming obsession and negative public perception of pyrometallurgy include greater carbon dioxide emissions and energy consumption per unit, associated with current hydromet technologies. Specific examples for copper and cobalt produced via the different routes are provided. The poor science involved with the global warming hypothesis is discussed. The use of LCA with sensitivity analysis as a decision making tool for mineral processing projects and technology developers is discussed.

Jan 1, 2004

The rights of nations to explore and exploit minerals in the continental shelf were recognized by the 1958 Convention on the Continental Shelf. The Commonwealth Government has expressed the view that, as a party to the Convention, it has, by virtue of its foreign affairs power, full rights to legislate with respect to offshore minerals. States have taken the view that the rights recognized as extending into the continental shelf are land mineral rights, which belong to the States, and the Commonwealth legislative power in this field is strictly limited. Without prejudice to each other's rights, Commonwealth and States agreed to "mirror" legislation in relation to offshore petroleum. Commonwealth and State legislation, of which the operative parts are in identical terms, are both administered, in relation to areas adjacent to each State, by State Ministers of Mines. The legislation has functioned well in practice, though difficulties are encountered by the Commonwealth Government due to lack of direct accountability to Commonwealth Parliament. An alternative scheme designed to overcome this problem is outlined.

Jan 1, 1974