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Comminution of solids is surely one of the oldest technologies which even in this day and age of DNAs, chips and space exploration continues to challenge our scientific acumen and engineering ingenuity. In essence, this challenge is two-fold. One, as much as three to four per cent of all electric power generated world-wide is consumed in crushing and grinding primarily because the utilisation of energy is woefully poor. Studies have shown that the efficiency of mechanical size reduction processes is of the order of 1.5 to 12 per cent only (Schoenert 1986). Two, with the grinding technologies available to us, we have, at best, inadequate and, at worst, almost negligible control over the shape of the comminuted particles, size dispersion of the ground mass, and the sharpness of mineral liberation. Low energy efficiency and lack of control in the sense mentioned above have far-reaching implications for resource conservation, performance of down stream unit operations, and damage to the environment. Our problem is in fact central to the mineral-energy resources triangle shown in Figure 1 which depicts the close interrelationships among mineral resources which are becoming poorer in content and more complex in mineralogy each day, energy resources which are depleting rapidly without any viable alternate on the horizon, and environmental concerns which can no longer be ignored. It is evident that any improvement in the efficiency of the comminution process impacts directly on the control of environmental damage, conservation of energy and the economics of the operation. These concerns have special relevance for the processing of non-ferrous ores.

Jan 1, 1992

By Wilkinson RDB, Van Der Meer FP

In order to overcome the statistical limitations imposed by the need to recover density tracers by hand, magnetic density tracers were developed to determine the efficiency of dense medium separators treating porous materials. The tracers were manufactured by extrusion of polypropylene ferrosilicon mixtures and subsequently coated with a distinctive paint to allow hand sorting according to density. Fifteen tracer batches were manufactured in the range 1.61 - 1.94 g/cm3. The tracer densities were determined by a hydrostatic method. The tracer method was applied to the dense medium separation of a Moroccan oil shale in a pilot scale Dyna Whirlpool separator. For each test, about 20,000 tracers were added with the plant feed and subsequently recovered from the products with a dry low intensity magnetic separator. The Tromp curve determined by conventional heavy liquid analysis was displaced towards lower densities compared with that determined by tracers, indicating that the porous shale particles absorb heavy liquid. It is concluded that for porous materials like oil shale and coal, the tracer method gives the most accurate results. In pilot scale testwork the tracer method is also much faster than the conventional heavy liquid analysis, as rather large samples have to be processed by the latter method to ensure Representativeness.

Jan 1, 1987

This paper describes the oil engihe plant owned and operated by Gold Mines .of Kalgoorlie Limited, and gives some details of installation, operational, and maintenance experiences which have arisen during the years of service, the last 5 years of which have been under the writer's control. Nos. 1, 2, 3 and 4 alternator units have run 50,276, 48,006, 49,677 and 25,930 hours respectively, and much knowledge has been obtained of their performances and faults. During the war years, it has not been easy to obtain spare parts; this, coupled with the loss of No. 4: alternator unit to the Commonwealth Government, made operation and maintenance a very difficult problem.All engines are of the enclosed vertical, single acting, 4-stroke cycle, airless injection type.The electrical power plant originally consisted of four 6-cylinder Belliss & Morcom heavy oil engines, direct coupled to Bruce Peebles alternators, running at 375 r.p.m., and generating 3-phase electric power at 3,300 volts, 50 cycles.No. 1 unit, installed in 1936, is a 6-cylinder 450 b.h.p. standard 12A Belliss & Morcom heavy oil engine, direct coupled to 280 kw. 0.8 p.f. alternator. The remaining three units are 6-cylinder, 660 b.h.p., lSA oil cooled piston type Belliss & Morcom heavy oil engines, direct coupled to 410 kw. 0.8 p.f. alternators, making a total capacity of 1,510 kw.No. 4"alternator. unit, an 18A Bellis.& Morcom set, was taken over by the Commonwealth Government in June 1943.

Jan 1, 1945

Bacterial leaching of sulfide minerals are fairly well established in heap, dump and in situ leaching and the primary bacterial treatment of refractory gold concentrate using CSTR have gained industrial prominence in recent years. Three cultures, a mesophile T ferrooxidans (DSM583), a moderate thermophile Sulfobacillus acidophilus (strain YTF1) and a extreme thermophile (Sulfolobus strain BC65) were used for the biooxidation (pre-treatment) of the Porgera gold-bearing pyrite concentrate under optimum O2 and CO2 enriched air (30 per cent O2 and ten per cent CO2) based on volume ratios. The positive effect of using oxygen and carbon dioxide enriched air for the biooxidation of gold-bearing pyrite mineral was clearly demonstrated where an increase in Fe release rate by a factor of 2.8, 1.8 and 1.5 for DSM583, YTF1 and Sulfolobus respectively were observed compared with the shake flask tests. The lag phase observed with the other test conditions such as in shake flask or with air decreased by about 80 per cent for all three cultures. The average observed dissolved oxygen concentrations in the pulp for these tests were 8.7, 5.8 and 5.0 mg/L for DSM583, YTF1 and Sulfolobus respectively, indicating that O2 was not limiting in these tests. The pulp redox potential was observed to increase with time for all tests coincident with the leaching rate and reaching a maximum of 663 mV, however the maximum value differs for each strain, with DSM583 exhibiting the highest followed by YTF1 and Sulfolobus. Biooxidation of pyrite under optimum gas enrichment at different pulp densities showed near total Iron extraction occurred for pulp densities of three, ten and 20 per cent (w/v). At high pulp densities, more so at 40 per cent than 30 per cent (w/v), the leaching rate decreased rapidly for tests with YTF1 and Sulfolobus. Monitoring of dissolved O2 shows that O2 demand increased with increasing pulp density and the average dissolved O2 concentration observed for YTF1 and Sulfolobus at 40 per cent solids concentration was 1.0 mg/L and below, suggesting limiting oxygen and carbon dioxide conditions for these two cultures. The decrease in leaching rate observed at high pulp densities (30 and 40 per cent) under optimum gas enrichment was accompanied by low metal dissolution and low redox potential values which was attributed to shear stress due to attrition of cells by high solids concentration, toxicity of metal ions especially Ag and Fe and the formation of precipitates and jarosites as confirmed from XRD analysis of leach residues hence impeding the leaching process. Limiting conditions due to high pulp density and viscosity were only observed for YTF1 and Sulfolobus. The subsequent cyanide leaching for precious metals from the pre-treated pyrite concentrate in all cases shows the extent of gold and silver recovery increased with the degree of pyrite oxidation and Au and Ag recoveries in excess of 80 per cent were achieved compared with only 18.1 per cent and 35.9 per cent for gold and silver respectively when treated by direct cyanide leaching on the original, untreated concentrate.

Jan 1, 2004

Pyrrhotite is pyrophoric when in a finely divided form. The problems of disposing of large quantities of finely divided pyrrhotite separated out by metallurgical processing from ore are formidable. In the case of an underground mine, a solution to the problem of disposal is to place the pyrrhotite in the stoped out areas and seal from any air supply. Further, the pyrrhotite could be diluted with tailings which would reduce the possibility of combust- ion. Several enquiries to various centres and authorities have shown that the products of the slow oxidation of pyrrhotite with moisture present can cement an inert matrix into a stable fill similar in physical prop- erties to fill stabilised with Portland cement. Stabilised fill can be used to advan tage with a suitable mining method to provide high recovery. The investigation demonstrated that air and 15% w/w water must be present for the fill to harden and that the sizing of the particles is a critical factor in drainage of a hydraul- ically placed fill and subsequent even harden- ing of the fill in a stope. With the materials used in the experiments in which the - 51 micron component of the tailings had been dis- carded, an optimum mix was found to contain 4:1 tailings/slag ratio and an overall pyrr hotite concentration of 8% (all proportion by weight). Approximately 34 days after drain- age to 15% moisture in natural air flow condit- ions, an unconfined compressive strength of 1.862 MPa was attained. A subsequent experi- ment was conducted with a sample of optimum mix in a pipe one metre long in forced air flow conditions. At a superficial velocity of 3.Om per hour the mix required 155 hours to harden to 1.862 MPa after drainage to 15% w/w moisture content. The pressure drop bet- ween the top and bottom of the mix in the pipe remained constant at 9 KPa/metre length. This result suggests that forced air flow conditions will increase the rate of hardening. No dangerous effluents were detected in the course of the experiments which could affect mine equipment or personnel.

Jan 1, 1973

By Anderson C. G

The design of crawler-mounted conveyor belts installed for the handling of brown coal in open cuts is described.INTRODUCTIONThe State Electricity Commission of Victoria operates two brown coal open cuts at Yallourn, Victoria. The larger of these cuts produces n million tons per year of brown coal containing 67 per cent. moisture, and the smaller, at Yallourn North, produces 1-1 million tons of coal, with a moisture content of 50 per cent. A further open cut at Morwell with projected output of 9-10 million tons per year is in the course of development. In the larger Yallourn open cut coal is excavated by means of conventional bucket chain and bucket wheel dredgers and transport is by electric locomotives and saddle bottom trucks running on 90 cm. gauge railway tracks. At Yallourn North, coal until recently has been largely won by 3i and 5 cu. yd. electric shovels and transported by large diesel-enginedmotor trucks. The difficulty of keeping these trucks in operation during the winter periods owing to the v.ery wet conditions and the high cost of maintenance of these vehicles led to the introduction of a moving face conveyor system.EXISTING CONVEYOR INSTALLATION AT YALLOURN NORTHA conveyor system employing a 36-in. belt running at a speed of 400 ft. per minute and having a nominal capacity of 425 tons per hour with 50-h.p. drive units, was selected as appropriate for the output of the open cut. The conveyor structure adopted was a standard type as used in under...

Jan 1, 1955

Some attempt to minimise the importance of the greenhouse phenomenon. They do so by observing that global temperatures are still within the range of recent variations and that it is still not possible to predict with any certainty what the precise consequences of greenhouse will be. Both observations are true though the conclusion is dangerous. Ice core samples from the Antarctic and Greenland have established the composition of the atmosphere and global temperature over almost the last 200,000 years. The profile of these twin variables shows that they have moved together; when the concentration of CO2 has been up, the temperature has been up and when the former has been down the temperature has also been down. Over almost 200,000 years the CO2 content has ranged between lows of 190 ppm and highs of 270ppm. In just 200 years of industrialisation the CO2 content of the atmosphere has increased to 350 ppm, 50% higher that the mean of the last 200,000 years and 30% higher than at the start of the industrial age. Carbon dioxide is now increasing at 0.5% p.a. Methane, about twenty times more effective than CO2 as a greenhouse gas has doubled in concentration in the last two centuries and is now increasing at about 1.1% p.a. Methane, nitrous oxide, chlorofluorocarbons together with a number of lesser gases will double the greenhouse effect due to in creased CO2 over the next 40-50 years.

Jan 1, 1989

By Whiten WJ

Although cone classifiers have received little attention in the modelling of mineral processing units they are one of the oldest non-mechanical classifiers. Their use has enjoyed a revival in recent years because of their low cost of installation and operation. In this paper the development of models for cone classifiers is reviewed and a new model is proposed. The experimental work, data collection and analysis are briefly described, and the new model is presented and discussed. The data used in the model development are made up from three distinct experiments using different units in each case. There are 21 data sets from a 3 m cone treating the tailings in a copper concentrator, 24 data sets from a 0.3 m pilot-scale cone, and 29 data sets from a laboratory glass funnel (0.(Y73 m diameter) used as a cone classifier, giving a total of 74 data sets. The model structure was developed from an analysis of particle settling in classifiers, using specialised model building software. The size of a particle settling in a separator and the forced flow through the apex of the cone were related via hydrodynamic dimensionless groups to the operating conditions of the unit. The model predicts the separation efficiency using the following four parameters: efficiency curve shape factor, cut-point, underflow density (per cent solids) or underflow pulp velocity. The model covers a range of feed flowrates from 1.2 to 5000 1/min.

Jan 1, 1993

By Winter W, Steele DA, Trudu AG, Gray CM

The Luzon arc extends for about 900 km from Taiwan to the island of Mindoro (central Philippines); in this area late Tertiary to Recent volcanism is considered to be the result of eastward subduction along the Manila Trench. The arc is composed of five segments, all of which have individual characteristics with respect to tectonic setting and magma chemistry (Defant et al., 1989). From the north to the south these are (Fig. 1): (1) the eastern Coast Ranges of Taiwan and the islands Lan-Hsu and Lu-Tao (Taiwan Segment), (2) the islands off the north coast of Luzon (Babuyan Segment), (3) the Northern Luzon Segment, (4) the Bataan Segment, and (5) the Mindoro Segment. Defant et al. (1988) suggest that the Bataan and Mindoro segments of the arc, both of which are characterized by different isotopic compositions and levels of large ion lithophile element (LILE) enrichment in the lavas, are separated by a 'pull-apart' zone, the Macolod Corridor.We are currently studying the mineralogy and petrochemistry of Late-Miocene to Pliocene volcanism in the Northern Luzon Segment (NLS), which comprises the geographic area of the Cordillera Central. This area has so far received limited attention, inspite of its wealth of porphyry copper, skarn and epithermal gold deposits. In this contribution we report the first results of our study of igneous rocks from the Mankayan Mineral District (MMD) which is located in the centre of the arc segment under consideration.

Jan 1, 1990

By Hegedus M

The Hydrogeological Survay of the bauxite mines in Hungary was establisned 30 years ago. The goal of the HS has been to collect the all available date needed to solve the hydrogeological problems of bauxite mines. The results of activity of the HS have been summarized in the annual reports-. This report is going to present a few methods to evaluate the hydrogeological properties of fissured, karstic rock ie. the evaluation of drilling mud losses, the statistics of core samples evaluated by a special computer program for calculation the porosity and permeability of the rocks. An experimental injection test is presented together with the development of a new portable instrument to get signes of the water table change during the injection test in every two second. It can be proved that the flow around the well may be a transient one if the yield of the injection exceeds a definite one (Figure 2.). It was observed that the permeability calculated from the pumping test date may be 1.2-1.6 time higher than it coming from the injection test. A practical example is presented also how to use the results of the HS for designing the dewatering of a new mine together with an analogous computer model to forecast the yield expectable for making the drift tunnel. A suggestion based on the hydrogeological feature has been done for the dewatering without using electric energy (see Figure 3.-6.).

Jan 1, 1988

Under South Africanncoalmining conditions, in the majority of instances coal is won using the bord and pillar system without pillar extraction. Examples demonstrate that strata control policy has an effect on practically all aspects of mining: (1) the choice of mining method; ((2) degree of coal recovery; (3) effect on productivity; (L}.) integration of'-support techniques with other operations. This is confirmed by use of modern research results and computer simulation. Although the examples are drawn from South African experience, the conclusion is generally valid. Strata control problems cannot be solved in isolation but as an. integral part of overall mining policy.

Jan 1, 1971

By T Christopher

The Campamento Au/Ag deposit, discovered by Linear Gold in 2004, is located in Chiapas State, southern Mexico. The deposit is hosted by a sequence of Pleistocene-Pliocene andesitic volcanic rocks that have been intruded by a feldspar-phyric porphyry complex. Measured and indicated resources are 852 000 oz Au and 3.46 million ounces Ag with inferred resources of 374 000 ounces Au and 920 000 oz Ag. Resources were estimated at a 1.0 g/t Au equivalent cut-off. This is an ABSTRACT only. A full-length paper was not prepared for this presentation.

Jan 1, 2008

By Collins BJ

Basic principles of stack injection are outlined and supported by calculations of thermal, chemical and aerodynamic requirements of an ideal 4000 tpd furnace. Calculated results show that these requirements vary with conversion of FeO, and that best performance may be expected with XFeO = 1.0 for which calculated production is 6919 tpd and coke rate is only 211 kg/thm. Calculations are also presented for a cycled injection. Discussions show that stack injection is a good way of overcoming softening problems and meeting the demand for iron in a fluctuating demand situation when it exceeds the maximum capacity of a furnace.

Jan 1, 1975

As previously advised, two of the raw materials for Wilsons Portland Cement are cement rock and limestone, both of which are quarried by the company. We now wish to give you a brief outline of these operations. The major material, cement rock, is obtained for our Portland Quarry at Tikorangi Hill, which is one mile west of the Works and a familiar landmark to travellers on state Highway 1. The geological structure of this deposit is involved, having intensive and irregular earth movements interpreted as large scale slumps where older rocks overlay younger rocks - numerous folds, faults and overthrusts are clearly visible.

Jan 1, 1978

As an indication of the overall quality for the three periods the expected run of mine ashes are given. Operating Period R.O.M. Quality Years 1 - 4 22.0% Ash (db) Years 5 - 14 18.8% Ash (db) Years 15 - 20 17.3% Ash (db) The size distribution of the coal was found to be generally as predicted in the 1980 study. However the ash, particularly in the smaller fractions, was found to be higher due to the previously mentioned friable nature of contaminant material. Following evaluation of this additional information, the proposed washery design was reconsidered. Three basic process schemes were examined. 1. A jig with two-stage heavy medium cyclones and spirals for treatment of three different size ranges. 2. A heavy medium vessel, two-stage heavy medium cyclones and spirals for the different size fractions. 3. A jig for initial treatment of the total feed (that is all sizes) with single-stage heavy medium cyclones and spirals for rewashing of the intermediate and smaller size Fractions.

Jan 1, 1986

The Yilgarn Block of Western Australia presents (figure 1) a number of problems for conventional diamond exploration based on heavy indicator mineral sampling. These problems are due to the geology and unique geomorphological development of the Yilgarn Block.Essentially the Yilgarn Block is a pene- plain developed on a craton composed of Archaean intrusive granitoid rocks with meta- morphosed greenstone; which, apart from regional uplift, has not been tectonically disturbed since planation by glaciation in the Permian. Therefore since the early Plesozoic the Yilgarn Block has been subjected to terres- trial weathering conditions. Bettany et al., (1984) identify two phases of particular importance in the development of the present landforms: 1. Periods of lateritization during the Tertiary which result in the ~lassi~al laterite profile (figure 2). Duricrust indurated : Fe and Al oxides Mottled zone : Clay and Fe oxides Saprolite or pallid zone : leached clay grading into fresh rock. 2. Subsequent periods of aridity and semi- aridity during which laterite development was truncated and reworking of laterite Occurred.

Jan 1, 1988

By Bucknell WR, Clarke DE

The paper provides a company's view of the relative merits of various valuation methods and outlines the basic approach it takes to the valuation of an exploration property. The negotiating process and methods of acquiring an interest in an exploration property is discussed The valuation methods discussed are: 1. Exploration Expenditure. 2. Real Estate. 3. Joint Venture Terms. 4. Rule of Thumb. 5. Net Present Value - Discounted Cash Flow. 6. Geoengineering.

Jan 1, 1994

The main iron ore deposits of Western Australia fall into three very different geological classes, which are, in order of importance: hematite enrichment ore, pisolitic limonite ore, and sedimentary ore. These are presently (1973) being mined in the approximate proportions 20 : 2 : 1, while the equivalent proportions for reserves are, very approximately, 200 : 70 : 1. Two minor categories which mar- ginally qualify as ore are detrital material variously referred to as scree ore or canga, and potentially beneficiable iron formation. These two latter types are dealt with very briefly, and the three main categories are dis- cussed in order of economic significance. Hematite enrichment ore results from the selective replacement of a pre-existing host rock by hematite. Almost without exception, this host is cherty banded iron formation (BIF); but certain exceptions have great genetic inter- est. Ore bodies of this kind occur both in the Archaean BIFs of the Pilbara and Yilgarn Blocks and in the Proterozoic BIFs of'the Hamersley Basin. It follows from their virtual restriction to a single kind of sedimentary host that there is strong stratigraphic control over the shape of ore bodies: these may be almost flat, of dyke-like form, or of complex configuration, according to the pre-enrichment structure of the host bed. This structure was an important control over the position in which ore formed:

Jan 1, 1973

-in 1961,.West Australian Petroleum's Eneabba. No. 1 bore encountered twenty-two' seams of coal totalling forty feet in thickn' ss between the..'depths of 6373 feet and 64,/,1 feet. 0n'ana:lysis; this coal had a. similar calorific value (8000 - 9000 B.

Jan 1, 1964

IN preparing a sample of refined lead for analysis, it is necessary to exercise great care to avoid contaminatien, as the amounts of the various impurities present in market lead are very small. The lead is cut into convenient-sized pieces, which are flattened out with a hammer, so that, on putting tbe lead through the rolls, strips of about one inch in width and Ij32iu. in thickness are obtained. The hammer, anvil, and rolls should be carefully cleaned before use. The strips oflead are cut up into pieces of about one inch square. If the lead is roIled out very thin and cut up into small pieces there is considerable risk of the acid acting too violently and causing loss through frothing over. A blank assay on all the reagents used should becarried right through, along with the actual analysis of the lead. This is of the greatest importance, particularly with regard to the determination of such impurities as iron, sulphur, arsenic, and antimony.METHOD OF ANALYSISThe method of analysis is as follows: Take two lots of 600 gIm. each, place in a large beaker, add 2000 cc. distilled water and 750 cc. concentrated HNOs. Cover with a clock glass and warm on a hot asbestos plate until all action ceases. (If any white precipitate forms, filter off and examine for Sn and Sb.) Add 420 cc. H2S04 (1-1), and stir well while adding the acid: Allow PbS04 to settle, pour off the clear liquid into a 12-in. porcelain evaporating dish, and start evaporating down, the dish being placed directly on an 8-in. ring gas burner. Wash the precipitate three times by decantation using approximately 1200 cc. hot water for each washing, and stir well...

Jan 1, 1922