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By Smith DM Jr

Silver deposits, in which silver forms at least fifty percent of the value of the ore, are abundant and large on the east side of the Pacific and are absent in the western Pacific. To determine if this uneven distribution is related to features of consuming plate tectonic boundaries which dominate the metallogeny of the Pacific Rim, the variation of Ag/Au in porphyry copper deposits was used to estimate the relative silver content of magma generated in subduction zones. Porphyry copper provinces with high Ag/Au occur in regions of the eastern Pacific where silver deposits are abundant, suggesting that the distribution of silver deposits is controlled by the relative abun- dance of silver in subducted ocean crust. Ocean crust being subducted in the eastern Pacific is mostly less than 50 million years old in contrast to most ocean crust in the western Pacific which is much older. Enrich- ment of silver in young ocean crust at spread- ing centers may reflect metallogenetic evolution over geologic time. Silver may be transported to the surface in volcanic rocks, and deposits are common where felsic varieties are abundant. The high ,solubility of silver in natural waters provides a natural storage mechanism for silver weath- ered from these rocks and ultimately circulated in near-surface hydrothermal systems where many silver deposits form. The regional distribution of silver deposits is not influenced by discoverability, vertical metal zoning, or regional tectonic style. The effect of igneous differentiation is unclear.

Jan 1, 1987

The operation of a one tonne submerged combustion pilot plant for the recovery of copper from anode furnace and converter slags is described and the effects of variables discussed. Using coal as reductant, copper levels of anode furnace slag were lowered to 1% or less, with batch times of approximately 120 minutes. Fluxing with limestone was required to produce a fluid slag at temperatures of 1200 - 1300¦C. For converter slags, reduction to 0.5% Cu or less was achieved in batch times of 35 minutes. The chemistry of the pyrometallurg- ical recovery of copper is briefly reviewed in relation.to copper recovery methods.

Jan 1, 1978

The present practices in electro-refining of copper are shown to be the result of piecemeal and gradual improvements and innovations as metallurgists responded to changing cost pressures and the availability of new technology.Major changes were inhibited by capital cost restraints and a reluctance to build unproven ideas into new plants.It is suggested that the level of technology available today, combined with the greatest cost pressures the industry has known, call for fundamental re-appraisal and a questioning of widely accepted conventional practices.Examples of the industry reaction to changing pressures are given, and directions for future developments are suggested.

Jan 1, 1985

Amongst the Pacific Rim countries, Papua New Guinea (PNG) is the leader in new gold discoveries and developments leading to new production. PNG has shown a dramatic increase in gold production when taken from a base of about 600 000 ounces in 1984 to 1 160 000 ounces in 1986. 1987 is expected to produce about 1 500 000 ounces and new planned developments will give further large increases. PNG's leading position when compared with neighboring Pacific Rim countries is only partly due to its favorable geological setting along the "Rim of Fire" epithermal zone. More important have been well-thought-out mining development legislation and good administration as well as consistent taxation and royalty policies. A stable political environment and a track record of new mining developments over the last 15 years, both pre and post Independence in 1975, have also been important factors in encouraging the new developments. Early Portuguese explorers associated the New Guinea mainland with gold as early as 1525 but it was not un,11 1R77 that a small ill-fated gold rush gave the first recorded production at Laloki near Port Moresby. Modest but commercial discoveries were made in the outer islands and coastal mainland regions from 1888 to 1926. In 1922 William "Sharkeye" Park found gold at Edie Creek and this led to major discoveries at Wau and Bulolo which were the first large scale commercial gold Operations.

Jan 1, 1987

By Morrison RD, Simmons CJ

A bewildering array of process control instrumentation is currently available for mineral processing plants. For sequencing control, special purpose microprocessors or the process control computer can be used. Where continuous control is required, then the choice is between pneumatic controllers, electronic controllers, shared display micro- processor systems and direct digital control. The benefits of each system are discussed and the advantages of using direct digital control in mineral processing plants are outlined. The factors which need to be considered when selecting control systems for new plants are listed. Instrumentation systems designed by Fluor Australia are used as case studies to illustrate the selection process. For established plants, conversion to direct digital can be advantageous, and case studies are given. However, replacement of existing systems requires justification based on a productivity improvement which will allow the control equipment to be paid for within a specific time period. Productivity improve- ments maybe assessed in terms of increased

Jan 1, 1978

By Yongjin S

Datong coal Mine suffers from delays and sudden caving of its massive competent conglomerate roof. Detailed geological studies of the nature of pebbles and matrix of the conglomerate and its sparse bedding, joint and fracture structure, gave rise to investigation of water injection to destroy its strength and to control caving. Comparative investigations, including porisity, permeability, compressive strengths and water injection of conglomerate and sandstone led to empirical expressions relating various properties and to guidance for effective injection and caving practice. This new safe roof control practice should be even more improved with further research, including Modelling.

Jan 1, 1992

A thick sequence of alkaline intrusions and volcanic rocks underlies a Quaternary caldera on Liliir Island. The sequence is host to a still active sub-aerial hydrothermal system and associated epithermal gold mineralisation. Sub-horizontal alteration horizons exhibit progressively increasing chondrite norma-lised (La/Lu) en and (La/Sm) cn ratios from unaltered shoshonites, to the potassic alteration zone, to the argillic altera-tion zone to the advanced argillic alte-ration zone. The increasing fractionation of HEE, and especially of LHEE, up the alteration sequence is the result of de-creasing pH, temperature and alkalinity of the hydrothermal fluids with increa-sing alteration intensity. HRE3 were especially mobile in argillic and advanced argillic alteration units characterised by acid fluid conditions and large fluid volumes. Abundant Cl, S and CO2 within the hydrothermal fluids and thus abundant REE complexing agents and large fluid volumes favoured the mobility of REE during hydro-thermal alteration of the volcanic rocks and intrusions. Steam escape, mixing of the gases with groundwater and a change from a magmatic neutral chloride hydro-thermal system to a meteoric acid sulphate system was accompanied by liquid/vapour ratio changes, pronounced alkalinity, pH and temperature decreases, and fluid/rock ratio increases. This caused the mobili-sation, fractionation and deposition of PF.F.

Jan 1, 1990

My early experience with the coal industry was in the latter half of the 1970s, where attention to only ones own æaccidentsÆ and concentration on behaviour controls were impeding the introduction of effective engineering controls such as ROPS, FOPS, roof support and residual current devices. Lack of the broad picture of personal damage and of relevant veridical (true saying) knowledge and data had to be overcome to achieve progress in reducing fatalities. Thirty years on, it is again necessary to take stock. How good is our knowledge, our data, our information on which we make decisions. Despite Australian all industry 1992-93 data showing 80.5 per cent of costs came from occurrences which permanently altered peopleÆs lives, New South Wales is still the only state reporting permanent disabilities. In 1991 - 1992, the rate of permanent disability per 1000 wage and salary earners was two. In 2000 - 2001, it was over four û more than doubled. Also strongly motivating is the huge cost. Industry carried 25 per cent of the $34.3 billion costs for 2000 - 2001, up ten per cent of 82.8 billion if the costs of pain, suffering and early death are included.

Jan 1, 2005

Modelling of Synergistic Effect of Cyanex 302 and D2EHPA in Zinc Solvent Extraction A comprehensive model is presented to predict the synergistic effect of D2EHPA and Cyanex 302 on co-extraction of zinc and manganese. The experimental results indicated that pH, temperature and the extractants ratio have strong effects on the extraction process. Correlations were proposed to predict the distribution coefficient of zinc and manganese between two phases at different conditions by multiple linear regression. The correlations were simplified by eliminating less important terms by analysis of variance. Optimum conditions (ie pH, temperature, extractants ratio and aqueous to oil phase volumetric ratio) for obtaining maximum separation of zinc from manganese at different zinc concentrations and number of extraction stages were determined. For finding the optimum condition genetic algorithm was used. Comparison the model estimations and the experimental data show that the presented model has good ability to predict the behaviours of zinc extraction system over Cyanex 302 and D2EHPA.

Sep 13, 2010

By Smith JW

Studies of 13C/12C ratios of carbon dioxide in seam gases and in secondary calcites show that 1. In mines prone to carbon dioxide outbursting, the source of this gas is external to the coal. 2. Faults draining reservoirs of magmatic or primary carbon dioxide, rather than intrusives, are the most likely points of entry of carbon dioxide into mines. 3. The higher the concentration of carbon dioxide in seam gas and the wetter the mine, the lower the likelihood of secondary calcite occurring as a filling in cleats, fractures etc. 4. A -role played by carbon dioxide in promoting outbursting may be the conversion of calcite to soluble bicarbonate, the removal of this in mine water and the subsequent weakening of the resistance of the bulk coal to stress.

Jan 1, 1980

By R McConnochie, J V. Rowland, J L. Mauk

The Sovereign prospect in the lower Waitekauri Valley of the southern Hauraki Goldfield occurs in daciterhyolite flows and volcanic breccias of the Waipupu Formation. The lower Waitekauri Valley contains a series of NE to NNE-trending normal faults, and the Sovereign prospect lies in a NW-striking graben. The structure of the Sovereign prospect is complex. NE to NNE-trending veins and normal faults dominate the area, however WWNW and N to S-trending structures occur locally. Kinematic analysis of these structures indicates predominantly dip-slip movement, with a local strike-slip component. At least two sets of veins occur in the area: 1.        steeply dipping veins; and 2.       low angle veins, which cross-cut and locally offset the steeper dipping        vein set. Mineralization appears to have formed during normal faulting in an extensional regime.

Jan 1, 2007

The Directional Drill Monitor (DDM) is an advanced instrument for real time in hole surveying. It was developed by Du Pont (Australia) to suit Australian gassy coal mining conditions. The instrument consists of three units: i. Down hole transmitter ii. Acoustic transducer iii. Data receiver processor unit (i.e. up hole unit). This paper describes the function of each unit in detail and highlights the importance of the DDM in long hole drilling efficiency. Surveying is carried out independent of hole depth. Each survey takes 2-3 minutes to complete, the frequency of surveying to control borehole trajectory is determined by the accuracy required for a particular hole.

Jan 1, 1992

By Smith KS

Mineral-deposit geology, geochemical processes, and biogeochemical processes are fundamental controls on the environmental conditions that exist naturally in mineralized areas prior to mining, and that result from mining and mineral processing. Input from economic geologists and geochemists is therefore crucial to effectively predict, assess, mitigate, and remediate the environmental effects of mineral-resource development. Recent open pit gold mining at Summitville, Colorado, has received intense public scrutiny for a variety of environmental problems, most important of which has been extreme acid drainage. Now a Superfund environmental cleanup site, Summitville exemplifies how economic geology and geochemistry principles (1) could have been better utilized to first predict and minimize the environmental problems, and (2) can now be used to optimize the environmental cleanup.

Jan 1, 1995

Around no subject of technical )uterest have prejudice and wrong-thinking in the past so wrapped a web of obscurity as that of the corrosion of metals.It is a matter which has primarily concerned the engineer, but the paucity of his training in chemistry and electrochemistry has been the stumbling block to a better understanding of its mechanism.Now that the more important conditions controlling corrosion have been scientifically.established, it can be seen that, with the exception of but a few of the minor points, the electrochemical laws enunciated by Faraday, Helmholtz; Nernst, and others, are sufficient to include all the facts of the process.The word corrosion (derived from the Latin rodere-to gnaw) is so often wrongly applied that a definition at this stage would be useful. As now understood, it means the dispersion and waste of the useful solid metal by conversion into a useless compound which mayor may not be retained on or near the metal remaining.Commonly the presence of these compounds is regarded as evidence of corrosion, but the converse is not necessarily true; the lack of visible corrosion products on a clean surface of metal is no criterion of the absence of this change. It may be difficult to prove that the erosion of such a surface has been caused by chemical and not by mechanical effects alone.

Jan 1, 1932

Throughout the Kalgoorlie Field the dominant factors influencing all planned exploratory work are: firstly, the general geology of the district, and, secondly, the lode fracture pattern. Superimposed on these, there are innumerable faulting problems which tend to complicate the search for ore.In this paper it is proposed to deal primarily with the lode fracture pattern and to touch on the general geology only insofar as it affects ore distribution. So much has been written on Kalgoorlie geology that it would be impossible to review the literature adequately in a brief paper such as this. The basic facts of rock types and rock distribution are well established and the broad structure of the field is known in the central portion, though it is less well established towards the northern and southern ends.The latest descriptions of the general geology are those of Stillwell (1), and Gustafson (2), -and these represent the basis of current knowledge.GENERAL GEOLOGY.The field is six miles long and about one mile wide, the long axis trending north-west. The "Golden Mile," or heart of the mining 'area, covers a length of three miles in the southern section, and consists of a central core of quartz dolerite greenstone which merges into uralitic quartz 'dolerite on its western margin. The uralitic quartz dolerite is derived from an original quartz dolerite by a low grade...

Jan 1, 1948

The Olympic Dam Mine is a large, mechanised, underground operation currently producing 2.2 million tonnes-per-year of copper/uranium/gold ore. The mine is accessed via one shaft and one service decline. An additional 13 raise bored ventilation shafts have been completed to-date.Ventilation requirements are stringent in order to provide adequate dilution and removal of diesel fumes, radon gas/daughters and heat generated from both engines and wall rock.Due to the nature of the orebodies, the mine workings will continue to expand laterally necessitating the addition of at least one major surface raise every year.

Jan 1, 1992

By Muir D

A review of the various methods of degrad- ing cyanide either from gold processing liquors or electroplating baths is presented with some discussion on their relative merits or problems. Whilst alkaline chlorination is common practice in many U.S. and Canadian plants it poses particular problems for certain plants. Alter- native methods include electrolysis, hydrolysis and air oxidation with activated carbon as catalyst which are also integral steps in the carbon-in-pulp process. A basic study of the degradation of cyanide ion has been carried out therefore to determine the effect of temperature, oxygen and carbon. It is shown that carbon is an excellent catalyst for degradation by air and likely to lead to higher losses of cyanide in a C.I.L. circuit. Degradation by hydrolysis is important at high temperatures and high pH such as employed in the Pressure Zadra or Anglo elution processes. Carbon catalysed degradation of cyanide by oxygen in effluent streams may be an environmentally acceptable alternative to conventional chlorine degradation.

Jan 1, 1987

An examination has been made of the rate and extent of removal of carbon from scrap metal charges when the melt is exposed to atmospheres which are reducing or oxidising with respect to FeO at unit activity. The mechanisms of decarburisation of molten Fe-C-S- P-Mn-Si alloys with H2/CO/H20/C02 gas mixtures with controlled compositions at high or low concentrations of carbon in the melt in the presence and in the absence of sponge iron, in both slag free melts and in the presence of various slag forming additives are discussed. A significant quantity of carbon can be removed from the metal during the melting stage and under optimum conditions, a high percentage of metal recovery and low carbon can be obtained after exposure of melt to the above gas mixture with controlled compositions. The presence of ferrous oxide provided by poorly reduced ore in the charge and the use of controlled atmospheres facilitated the removal of carbon to very low level during the melting period.

Jan 1, 1984

By Scott RM

The project management and construction plans adopted by Davy McKee for the Cooper Basin Liquids Project resulted in a project notable for the Relatively short duration from initiation of the design through to liquids production. Two locations were involved, one at Moomba in the far northeast of South Australia some 800 km from Adelaide, and the other at Port Bonython some 40 km from Whyalla. Total expenditure by the owners at the two sites was in excess of $600 million. Matters covered include organisation, transport, construction, industrial relations, project services and commissioning.

Jan 1, 1986

By J du Plessis, W Marx

The FutureMine Collaborative Research Initiative has been successfully completed after three years of activity. The main objective of this initiative was to provide applications of research previously undertaken in the DeepMine initiative in terms of realistic solutions to problems facing gold mining operations as they reach for depths beyond 3500 m below surface. The FutureMine initiative was subdivided into four broad streams of technological expertise: rock engineering and seismicity; mining engineering and orebody management; software and communications and ventilation, cooling and refrigeration. This paper presents a summary of research output in this last area of expertise. Broadly, research in mine ventilation, cooling and refrigeration was directed in areas related to the recirculation of air, cyclical use of ventilation and cooling systems, air scrubbing technology, optimisation of chilled water reticulation, obtaining direct cooling at the workface, improving underground refrigeration systems through dry air-cooling and water heat rejection systems and a number of software simulation programs to be used in specific applications and as a tool assisting real-time monitoring of underground environmental conditions.This paper describes in broad terms the outcomes from this section of the research program and proposes ways in which some of these technologies may be combined synergistically in novel systems aimed at maintaining acceptable environmental conditions while reducing the impact on the profitability of operations.

Jan 1, 2005