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The presence of gold or tin in a particular place in payable quantities may be suspected from geological and prospE;cting reports. It behoves the engineer by judiciously spaced boreholes or pits to establish whether the place is exploitable with profit, and it is the purpose of this paper to set out the ways in which this is done. The various types of deposit to be considered occur in Malaya, Thafland and Borneo, in which countries the writer spent four years in estimating alluvials.The methods described were used in actual practice both by the writer and previous engineers for the same company. The subsequent exploitation of the alluvials evaluated by the methods given below shows that the recovery was as good as, and sometimes higher than, expected. No claims are made to the originality of the methods, but it is 'felt that they may be new to some engineers and< interesting to others contemplating alluvial testing.

Jan 1, 1942

Soon after the Rosebery concentrator commenced operations in 1936, an investigation was begun in an attempt to discover a substitute for cyanide in lead flotation. Cyanide is an excellent depressant for zinc and iron, but it also powerfully depresses the copper, silver and gold bearing minerals present in Rosebery ore, thus allowing them to pass through to the zinc concentrate or final residue where they are of little or no value.The investigation was not entirely successful, but it did indicate that sodium bisulphite or sodium sulphite could be used as a depressant for zinc without depressing the copper, silver and gold bearing minerals. The sulphites were, however, much inferior to cyanide as apyrite depressant.At about this time, I. W. Wark, using the captive bubble technique, had shown that, at the concentrations normally used, sodium aerofloat is not a promoter for pyrite or galena in alkaline solutions (see his book "Principles of Flotation", p. 188). Some preliminary tests on the production of a copper concentrate from Rosebery ore were therefore carried out using sodium sulphite as depressant and sodium aerofloat as promoter.The results of this work were promising but, since Rosebery ore usually carries only about 0·5% copper, there did not seem to be much incentive to carry the work further. With the outbreak of war, however, Australia became desperately short of copper and the relatively small amount in the ore. became of sufficient importance to...

Jan 1, 1952

Although the pattern of metamorphic zones south of the Thackaringa-Pinnacles Fault is much obscured by polymetamorphism, displacement of the orthopyroxene isograd by the fault agrees with the displacement of a horizon of "banded aplite" mapped by Andrews (1922). A dextral transcurrent component of 20,000 ft is indicated.INTRODUCTIONThe east-west Thackaringa-Pinnacles Fault (Andrews, 1922; King and Thomson, 1953), one of the major geological structures in the Broken Hill district, New South Wales, cuts across the general north-easterly strike of outcrops and fold structures of the Willyama Complex. The degree of shearing and recrystallization in its unusually wide crush zone and the manner in which adjacent rock units and structures have been dragged into conformity with its strike denote considerable movement on the fault. Information concerning the nature of this movement is of critical importance in the search for possible continuations or repetitions of lead-zinc mineralization south-west of Broken Hill.A transcurrent movement of 20,000 ft, with the southern block moving west, was estimated by Andrews (1922), who correlated prominent outcrops of "banded aplite" at The Pinnacles (north of the fault) and Big Hill (south of the fault). Displacement of this order, however, does not seem sufficient to explain the extent and character of the fault zone. Recent chemical and petrological studies of the banded aplites at The Pinnacles and Big Hill by Vernon (19B1) confirmed their similarity, but indicated an origin by metasomatic replacement of pre-existing folded and metamorphosed rocks. This raises the possibility that some...

Jan 1, 1965

In undertaking to write a few notes on practical mining in Bendigo, the great quartz mining centre of Victoria, which just now is celebrating its fiftieth anniversary of gold mining, satisfaction must be expressed which is, no doubt, shared by all mining men and inyestors, that Bendigo has not lagged behind other Australian mining districts in the evolution of mining from its crude state, subsequent to the discovery of gold in 185 to its present more perfect state; and though it may be said that it has not yet reached the high pinnacle of perfection towards which advanced science and change of conditions may yet lead it in the course of future progress, yet, what has already been done in this respect, the adoption of the most approved methods appliances and modern machinery, tending towards greater and still greater efficiency, facility, and economy in our mining industry, must be accepted as a guarantee that in tne future as well as in the past, progress in our means of developing our mining resources will ever remain our watchword, by means of which future difficulties will be overcome as well as they have been removed in the past.The adoption of this principal, combined with a study of rigid economy, has raised gold mining here, as well as in other places, from a state of speculation, and sometimes wild speculation, to the status of a solid, stable industry, the strong supportand backbone of the country in which it flourishes. Two of the principal factors which have been to a great extent instrumental in bringing about this satisfactory state, must be specially mentioned.

Jan 1, 1902

Traditionally, capital costs of major resource development projects have been estimated as a single amount to which a percentage accuracy has been assigned based on the method of preparation of the estimate, that is, on the amount of information available to develop the estimate.However, there is a growing recognition of the importance of a probabilistic approach to capital cost estimates, and of a more rigorous calculation of estimate accuracies and of the presentation thereof. Accuracies can be expressed with more certainty as a percentage of the estimate amount where the percentage represents one standard distribution on the probability curve for the capital cost of that specific project. Thus confidence levels can be stated for various estimated amounts - for example, it can be stated that there is an 85% chance that a stated amount will not be exceeded, or a 90% certainty that a (higher) amount will not be exceeded. Moreover, the right skewness of the probability distribution curve for most projects can be readily recognised and reflected in the evaluations. This enables senior executives and board members to have a clearer understanding of investment uncertainties, and the possible magnitude of commitments.

Jan 1, 1990

By Nageswararao K

A series of tests was carried out on one of the rock-pebble milling circuits treating complex nickel ores at Kambalda Nickel Operations of Western Mining Corporation. A mathematical model to describe the behaviour of a 508 mm hydrocyclone was developed from the data.A "flat" reduced efficiency curve was observed for the system. This was attributed to a marked difference in the specific gravity of different size fractions of the feed. A modified approach in describing the shape or the reduced efficiency curve resulted in accurate prediction of the hydrocyclone performance.

Jan 1, 1981

Ledcap Pty Ltd has developed two software tools for assisting in the determination of life-of-mine (LOM) trucking requirements. The first tool generates haul paths and the second calculates truck travel time over these paths. The two step approach allows the paths to be viewed and if required edited, to better represent the actual site haul routes.The first tool automatically creates haul paths between the mine bench and the dump. To do this the user supplies a master haul route and a scheduled block model. The master haul path and the block model are interacted to create multiple haul routes, one for each pit/dump bench pair in each scheduling period. Each path carries with it a record of the scheduling period it represents and the dry tonnage hauled over the path in that period.The second tool calculates truck travel time over the path. Data from the manufacturer's rimpull and retarder curves are used to calculate accelerations and speed over each segment of the haul path. As the paths are derived from digitised representations of mine haul routes the path f les often have over a hundred segments. This detailed representation of the haul route allows the software to automatically adjust speed for different radius corners and accurately simulates the changing accelerations over the gradient changes that occur in real life mine ramps. Rolling resistance can be specified at a global level, at a segment level and at a period level. This allows rolling resistance to be changed seasonally as well as spatially.Life-of-mine trucking studies attempt to calculate an accurate answer from extremely variable inputs. This paper will detail the features of the two software tools and how the tools provided in the software can assist the mine planner to have greater confidence in their life-of-mine trucking requirements and the subsequent production capacity inputs to their scheduling calculations.

Dec 6, 2010

Laboratory-Scale Magnetohydrostatic Separator for High Resolution Density Analysis of Plastic and Other Wastes Recycling and reuse of different plastic wastes is still a current problem to solve for process engineers and it is true for seeking industrial applications as well as for smaller laboratory-scale, where a given waste sample, plastic or even metallic, has to be precisely separated into narrow density fractions to gain data for industrial design or for scientific research. The principle of magnetohydrostatic separators are known even there are industrial size machines but our primary aim was the development of a laboratory-scale separator for analysis of particles of densities up to 6 kg/L and sizes up to 8 mm. Main parts of the built experimental equipment are the ferrite core with two high power coils. The shape of the ferrite core at the two sides of the separator channel was specially designed to produce isodynamic magnetic field. In these places the ferrite core was constructed from laser cut ferrite sheets. The development of the high power electric supply for the two coils was a real challenge because the high voltage and current (400 V, 30 A) and because it had to be precisely regulated for being able to set discrete relative forces on the particles. Two separator channels were made from transparent plastic. The magnetic fluid is circulated by a centrifugal pump, fresh feed is supplied by a vibrated feeder and products can be taken by built in samplers. The velocity profile in the separator channel is measured by an ultrasonic Doppler velocity meter. Paper reports about the development and itself of the magnetohydrostatic separator and about some fundamental and applied laboratory experiments with different reference particles and wastes from used cars and electrical appliances.

Sep 13, 2010

During the past Two years in reef gold mining, "indicators" have received great attention at the hands at the Victorian gold seekers. Many years ago, what was caned the" indicator lode," was struck in Ballarat East, on the course of which extremely rich deposits of gold were discovered but as to its being a .qeneral experience in reefs or leaders no one ever dreamed. Now, however, we find that these "indicators" are frequently to be met with, though they differ very much in different localities, making it, therefore, a difficult matter for other than a careful minel' to follow them. The necessity of following "indicators" for the purpose of developing gold is now recognized, and the policy of following them up has been attended with much success in this field. In the case of Messrs Shaw and Sons, at Wedderburn, those gentlemen began to work on an "indicator" here five years ago, and immediately thereafter more by accident than anything else they being at that time inexperienced as regards "indicators " came upon gold bearing quartz, which continued payable so long as the" indicator" aud the stone were in conjunction with each other, but as soon as they parted company the stone ceasedto be of any value then, by following the" indicator," as the latter intersected fresh bodies of stone they proved again more or less payable, until a fortnight or so ago the Messrs. Shaw turned out 4 tons of stone, which yielded £1,825, with also profitable workingup to the present moment. Where they are now working is a mile north of their original find thus proving that "indicators" travel considerable distances and have something to do with the gold deposits found in reefs. On the direct course of Shaw's "indicator," as high as hundreds of ozs to the ton was obtained from the stone but, just a few inches from either side in the same" leader," not a colour could be got. Whatever the cause-whether by electricity or some unknown force in nature-the gold is found on the course of these" indicators" and nowhere else, and-as each of the Victorian Government Geologists admit-their value to the gold-seeker as a means of leading to' gold cannot be over-estimated.

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

The geological features of the destructive plate margins of the southwest Pacific favour the formation of porphyry type deposits. The major controlling factor favouring the formation of gold-rich deposits of this type is a dense crust. This results in shallow intrusion of large magma bodies beneath andesite stratovolcanoes. Where the intrusives have near vertical sides, the comparatively low temperature of transfer of volatiles from the solidifying melt favours the partitioning of gold into bubbles of volatiles. They reduce the viscosity and density of the melt, resulting in the upward movement of a mineralised melt. With the drop of pressure with upward movement the bubbles separate into a two phase mixture, triggering freezing of the mineralised melt and the formation of a gold mineralised stockwork.

Jan 1, 1995

he Wyalong goldfields were discovered in September, 1893, Messrs. Neeld and Sons, owners of the principal mine, being the pioneer prospectors. During the earliest days of the field the ore was sent to Barmedman, a distance of eighteen miles, for treatment at a battery there. The field rapidly increased in importance, and it was not long before a public battery was established on the spot. After some considerable quantity of ore was treated by this process, it became apparent that battery treatment was quite unsuitable for the richer ores, involving, as it did, considerable loss in the tailings. Recognition of this fact led to the erection, in 1895, of plants by the Wyalong Chlorination and Cyanide Works, owned by Mr. Walter Sully, for treatment by their processes; followed, at a later date, by Messrs. Neeld and Sons Chlorination Works. The Wyalong Chlorination and Cyanide Works, after a delay of twelve months in the erection of their plants, have since catered continuously up to the present time for the requirements of the field.Their plant consists of a No. 3 Gates' rock·breaker, a revolving dryer, a No. 5 Krupp mill, revolving roasting furnace with finishing hearth, two chlorination vats of 20 tons capacity each, "nine cyanide vats of 30 to 100 tons capacity, two Wheeler pans and three chlorine generators. The ores are purchased outright on assay at a fixed scale of charges, and treated by the owner of the works on his own account.

Jan 1, 1903

By E A. Amaral Jr, A C. Chieregati, J C. O Souza

Cross-belt samplers are designed to sample particulate material in processing plants, usually when there is no space to install a conventional linear falling stream sampler. Most of the available cross-belt samplers are mounted on the top of conveyor belts, and remove each increment from a loaded moving conveyor with a 360° rotation of an open faced cutter, in a plane perpendicular to the material flow. Despite the practicality of this equipment and the fact that it occupies very little space in the plant, cross-belt samplers are well known for collecting biased samples, especially due to the increment extraction error. Sampling consultants around the world tend to condemn this sampling equipment, claiming that it is incapable of collecting the fine material from the bottom part of the load, and, since the sampling probability is not uniform for all fragments and depends on its position in the stream, this kind of sampler generates biased samples and its use should be avoided. Furthermore, the greater the segregation effect between particles, the larger the bias. However, some plants, whose initial design did not plan for the installation of a falling stream sampler, must rely on cross-belt samples for process control and reconciliation. For the past years, sampling equipment manufacturers have been putting effort in modifying the cross-belt sampler design in order to comply with the principles of correct sampling. Changes to the cutter material, shape, position, speed and movement in relation to the material flow have been made, and are continually being tested for different types of ore with various chemical and physical characteristics. This paper presents the improvements made to a cross-belt sampler at a gold plant feed in Brazil and describes the tests performed until it was possible to validate the new sampling equipment for reconciliation purposes.CITATION:Chieregati, A C, Amaral Jr, E A and Souza, J C O, 2017. Validation of a modified cross-belt sampler for reconciliation purposes, in Proceedings Eighth World Conference on Sampling and Blending , pp 247–254 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2017

Electrochemistry Measurement, Using Chena Analyser, to Investigate Selective Separation of Pentlandite and Pyrrhotite

Sep 13, 2010

The ultraviolet spectrum of isopropyl ethylthionocarbamate (the principal constituent of Dow flotation collector Z-200) in water and of Z-200 itself in water was found to have an absorption peak at 242 nanometers(nm). The height of this peak was found to be directly proportional to isopropyl ethylthionocarbamate concentrations up to 15 p.p.m. Z-200 contains about 90 per cent isopropyl ethylthionocarbamate and the heightof the peak was proportionately lower, but obeyed the straight line relationship up to 15 p.p.m. This showed the potential value of spectrophotometric measurements for the determination of Z-200 residuals in flotation liquors.Methyl ethyldithiocarbamate (an impurity in Z-200) increased the peak height slightly, but other impurities in Z-200, xanthates, and most inorganic salts present in flotation liquors do not interfere. However nitrate ion and thiosulphate ion have absorption peaks which overlap the isopropyl ethylthionocarbamate peak.The simplest general method to overcome this effect is to extract the isopropyl ethylthionocarbamate into cyclohexane and to measure the absorbance of the extract.The maximum absorbance of the cydohexane extract was at 247 nm and the peak height at this wavelength was found to be directly proportional to the isopropyl ethylthionocarbamate or Z-200 concentration in the original aqueous solution. An alternative method is to measure the spectrum of the original aqueous solution using the aqueous raffinate from extraction as a reference solution. This gives the spectrum due to isopropyl ethylthionocarbamate alone and measurement of the absorbance at 242 nm gives the concentration in the original aqueous solution. Both methods give the same value for the concentration of isopropyl ethylthionocarbamate in the original solution.

Jan 1, 1969

During the latter part of 1937 consideration was given to the construction of a; local smelting plant for producing blister copper. Previously copper concentrates had been shipped to the United States of America. The proposition had the advantages of a saving in cost of realization, quicker financial return and reduced dependence on overseas shipping.The smelter was designed by the existing staff, who had difficulty in obtaining data on small plants, particularly on the reverberatory furnace. Construction was started in March, 1938, and the reverberatory was blown in on January 16th, 1939. One roaster had been operating for several weeks prior to this date.While results and operating technique on this new departure in small-scale smelting are barely beyond the experimental stage, it is felt that the experience gained to this time should be recorded to help fill the obvious gap in published information covering plants of this type.At present there are three copper smelters operating in Australia; the other two plants are equipped with blast furnaces.LOCATIONThe new smelter is situated in a position convenient to the concentrator and to the power plant. The site is traversed on two sides by a brick flue, from an old smelter plant, which connects with a 250-ft. stack. This stack and portion of the old flue are used in connection with the...

Jan 1, 1939

Generating short- and long-term mine production schedules in isolation and independently from each other means that only a local optimum can be achieved when each scheduling phase is carried out. The globally optimal solution however, can be achieved when integrating scheduling phases and accounting for the interaction between short-term and long-term activities simultaneously. This paper addresses the task of integrating short- and long-term production plans by combining the short-term objective of minimising deviation to targeted mill feed grade with the long-term objective of maximising net present value (NPV) into a single mathematical model. A case study is presented which compares the present values of the same stope data set scheduled via separate long and short-term models and than by the proposed integrated model which applies a predetermined penalty for each tonne of metal deviation to target for the respective ore tonnage being processed. This allows an operation to obtain a globally optimal scheduling regime when taking into consideration the cost and loss of value resulting from fluctuations in grade to the mill over the short-term.

Dec 6, 2010

The limit of pressure to which an underground dam may with safety be subjected, is a question that-as far as the writer knows has not received the same attention from authorities on engineering construction, or practical mining, that has been accorded to questions on which the design and strength of other structures or machines in connection with a mine are based. That dams may, under certain conditions, be constructed to resist water under great pressure is a known fact. But the difficulty of demonstrating beforehand that any proposed structure of this kind will withstand the pressure and be effective is, owing to the indeterminate nature of some of the risks to be provided against, very great. In the present state of our knowledge it may almost be laid down as a rule, that a dam of this kind should not be undertaken where grave consequences would attend failure until experience of structures where the physical conditions are similar, but where there are no such risks, has given assurance that such work would stand.In Mines and Minerals for May, 1900, there is published a paper by Mr. James McNaughton describing the construction of three underground dams in the iron mining district of Michigan.The first of these was put in to hold back a flow of 750 gallons per minute, which when pent up created a pressure of 276 pounds per square inch, showing that the height of the sustained column was about 635 ·feet. The hole through which the water issued was in the bottom of the cross cut it was enlarged by removing all loose rock for a depth of 18 ft...

Jan 1, 1901

By J L. Mauk

 Broken Hills is an adularia-sericite epithermal Au-Ag deposit, hosted in flow-banded rhyolites and overlying rhyolitic pyroclastic rocks in the eastern Hauraki Goldfield. The 7.1 Ma deposit was the largest producer of gold in the eastern Hauraki Goldfield, and was one of very few economic deposits hosted in Pliocene rhyolites. This paper presents the results of a recent study in the upper levels of the deposit. Maps and cross-sections constrain structural and lithological relationships, and the lateral and vertical extent of a breccia pipe û the major feature of the upper levels.   Previous studies in the upper levels of Broken Hills have shown that gold and silver values are concentrated around and within a large breccia pipe, mined by a series of æcaveÆ stopes and in veins. Contour diagrams of Au-Ag data from channel samples indicate that the breccia pipe was a major fluid channel-way for mineralising solutions.   The breccia pipe deposits are part of the dynamic geothermal system that formed the Broken Hills ore bodies; they developed as a result of hydrothermal brecciation in areas of structural weakness within a rhyolite pyroclastic unit that overlies a massive rhyolite lava-flow unit. The main breccia pipe begins near the rhyolite/pyroclastic contact, having the shape of an inverted, inclined cone, and consists of silicified breccia, stringers of quartz, and irregular patches of clay-altered country rock. Smaller zones or pockets of hydrothermal eruption breccia are silicified and contain low grade gold in the matrix and in the adjacent silicified wall rocks.   Quartz has been classified according to its physical characteristics as seen in situ and hand specimens indicate that vein definition decreases upwards, perhaps as a result of changing lithological conditions and/or increasing proximity to the paleosurface. Hydrothermal quartz is widespread as veins and as a replacement mineral, or lining fractures and cavities and overgrowing rock fragments. Breccias contain vein quartz, but some quartz veins cross-cut breccias, indicating that vein and breccia formation was relatively synchronous and overlapped in time.   Disseminated gold-silver mineralisation is associated with vein quartz and silicic alteration of the wall rock within the breccia pipe. The auriferous zones are highly irregular and erratic, and sampling results show a wide range of gold-silver ratios, suggesting that highly volatile physiochemical conditions prevailed during mineralisation.

Jan 1, 2005

Metana Minerals commenced life in 1970 and graduated to a mining company in 1981 with the opening of a small alluvial tin-tantalite mine at Wodgina (W.A.) The present board of directors assumed control of the company in 1978 and established the exploration and development philosophies that have guided the company's expansion to its present status as an emerging diversified miner. An ability and willingness to raise equity capital when required has been a feature of the company. Company activities include exploration for gold, diamonds, heavy mineral sands, polymetallic (base and precious metals) deposits, strategic minerals, rare earths, oil and gas in a geographical distribution covering the entire Australian mainland Metana owns and/or operates four gold mines (Reedy, Mt Magnet, Youanmi and Howley) and at the time of writing is developing a fifth gold mine - its first underground mine - at Rothsay. In contrast to many similar or larger sized companies, Metana undertakes most activities itself rather than through the use of consultants or contractors. In-house services include: analytical and metallurgical laboratories, plant engineering design and construction, drilling and mining (earthmoving) Metana Minerals has established an enviable reputation for technical excellence and this expertise has placed the company in a sound position to continue its growth pattern into the future. This growth will be achieved through a combination of low cost and successful exploration and acquisition of suitable mines either directly or through corporate activity.

Jan 1, 1989