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By M Iglesias-Martínez

The potential for iron ore in the Central African Archean belts has received much less attention by comparison to their equivalents in other cratonic regions of West Africa, South Africa, Australia and Brazil. Historically, iron ore is known to occur in South Cameroon and North Gabon with significant iron ore deposits (eg Mbalam in Cameroon, Avima in the Republic of Congo, Minkébé, Bélinga and Boka-boka in Gabon), having been the subject of geological exploration programs carried out by government institutions and exploration companies. Although the presence of strong aeromagnetic anomalies, undeniably related to the presence of greenstone belt formations, has been recognised, this study is the first attempt to assess the potential of banded iron formations (BIF) in the Northern part of the Gabonese Republic in the region between Minvoul and Minkébé (>10.000 km2). Deep lateritic weathering, inaccessible equatorial rain forest and high operational costs are some of the reasons why only limited exploration has been undertaken in the area. This work aims to improve the geological knowledge and to highlight the potential for iron ore of the eastern margin of the Ntem Complex units dated between 3.3–2.7 Ga. Field work showed a series of mafic rocks (amphibolite, anorthosite and gabbro), schist and BIF (described as itabirites in neighbouring areas). Samples from Minvoul BIF showed an extensive and deep weathering to powdery hematite revealing the presence, in thin sections, of iron oxides including magnetite, hematite and martite, primary and secondary quartz, garnet, hornblende, anthophyllite, cummingtonite and epidote. Mineral assemblages and coarse grain size suggest a metamorphic grade ranging from medium to upper amphibolite facies. The existence of known economic iron ore deposits in neighbouring regions combined with an extensive weathering enrichment process are promising factors for potential iron ore discovery in this remote area.

Sep 18, 2023

By N Trabelsi, D Bakun-Mazor, Y Ben-Ari

As part of a comprehensive project to develop a remote sensing tool for evaluating the mechanical properties of rocks, one must obtain a rapid indication of these properties using conventional field methods. A common method for evaluating the mechanical properties of rocks in the field is to use a Schmidt hammer, a portable device that measures the rebound (R) of a spring-loaded mass impacting against the rock surface. Since the 1960s many studies have been made to find empirical correlations between the R value measured by the Schmidt hammer and mechanical and physical properties such as uniaxial compressive strength (UCS), elastic modulus, density, and porosity. Despite the existing correlations in the literature, this work is required to establish detailed empirical relationships for the carbonate rock units in Israel. To do so, 150 rock samples were collected from 38 different outcrops of carbonate rock units. In each outcrop, 20 impacts were made using a Schmidt hammer at different but adjacent points. The impacts were done horizontally perpendicular to the vertical rock walls. In the laboratory, we measured the density, effective porosity, water absorption, UCS, and elastic modulus. The rock samples we selected contained a wide range of UCS: from 7 to 270 MPa. Our empirical correlations indicate an exponential relationship between R and UCS and the elastic modulus, and linear relationships between R and density, porosity, and water absorbance. The most reliable index is the average of the five maximum impacts out of the 20 made in each rock outcrop. The correlation equations obtained from this work will make it possible to effectively evaluate the mechanical properties of the intact rock in the field, thereby aiding development of advanced tools for rock mass characterisation by means of remote sensing.

Nov 29, 2022

The introduction of on-stream analysis in flotation circuits has raised the possibility of automatic control of flotation performance by digital computers. The development of control strategies for an industrial zinc cir- cuit is discussed with reference to identifi- cation of the major disturbances, investigation into the performance of the circuit, the design of the control algorithms, the testing of their performance and their implementation in a production environment.

Jan 1, 1983

By Barrett D

The paper discusses the justification for the Open Pit Mining Operation at Central Norseman Gold Corporation Limited's North Royal facility.Open pit mining history is outlined together with production statistics and associated costs. Underground mining practice is discussed together with an outline of the problems with mining in oxidised ground.

Jan 1, 1984

By Pollard DM, Willis GM

The removal of bismuth from liquid copper in a vacuum furnace was studied over a range of pressures. The rate determining step changes from diffusion in the gas at pressures above 0.2 Torr to approach the Langmuir evaporation rate at pressures of 10-2 Torr. Oxygen and sulphur were found to have a negligible effect on the rate. Bismuth removal from copper sulphide was found to be considerably slower than from copper. This is consistent with the known thermodynamic properties of ternary sulphide melts.

Jan 1, 1980

Almost from the beginning of civilisation the inhabitants hadlearned the art of recovering and working copper to produceitems which were of use to society.From the early beginnings of the use of copper which can betraced back 6000 years and more, there has been an evolutionaryprocess accentuated in more recent times in which the art ofproducing alloys particularly with tin and latterly zinc and otherelements, has given society a wide range of useful alloys for usein industrial, domestic and architectural applications.

Jan 1, 1995

The Goonumbla district of central-west New South Wales, Australia, hosts four significant porphyry Cu-Au deposits that contain a combined probable ore reserve of 71.7 million tonnes at 1.2 per cent Cu and 0.5 g/t Au. Mineralisation in the Goonumbla deposits is associated with narrow, pipe-like intrusions of quartz monzonite porphyry, in which several intrusive phases have been recognised. Five textural characteristics have been used to distinguish the various intrusive phases recognised in the Goonumbla porphyry deposits: (1) phenocryst abundance; (2) nature of the groundmass; (3 and 4) proportion and mineralogy of the mafic and non-mafic phenocrysts; and (5) the presence or absence of anhedral quartz grains in the groundmass. In addition, each intrusive phase is classified according to its estimated original quartz, alkali feldspar and plagioclase contents. Features common to all of the intrusions are that they contain two types of plagioclase and two or three types of K-feldspar phenocrysts in variable proportions. Most of the intrusions also contain apatite micro-phenocrysts. The groundmass textures range from aphanitic through granular to euhedral K-feldspar in a quartz matrix. With only one exception, all of the intrusive phases recognised are either quartz monzonite porphyry or mafic (>5 per cent mafic minerals) quartz monzonite porphyry. The exception is a biotite - phyric monzodiorite, which occurs in the basal portions of one of the deposits. Textural variants of intrusive phases at Goonumbla have been investigated to establish whether specific combinations of characteristics indicate mineralised intrusions, while others suggest barren ones. Some correlations between intrusion types and Cu and Au grade have been recognised. The most important textural characteristic that relates to high grade mineralisation appears to be the low proportion of mafic minerals, because the quartz monzonite porphyry intrusions hosting most of the mineralisation in the two deposits studied contain

Jan 1, 1999

In the years prior to the outbreak of war in 1939 Australia's production of copper had declined from a peak of about 80,000 tons in 1911-1915 to approximately 25,000 tons in 1939. This production met the need of the slowly growing national requirement and gave an excess for export. However, with the intensification of the war effort in 1942 due to the imminence of a Japanese invasion of this country, or at least a blockade of the sea lanes, it became necessary to expand production of armaments, and consequently the demand for copper increased beyond the capacity of the industry. Importation of copper to Australia during the period 1940-1944 was 131,000 tons.When exploration of the Mount Isa orebody was first being carried out in 1928, No. ID diamond drill disclosed the presence of some copper ore lying outside the limits of the Black Star orebody2, but it was not until 1941-1942 that the development of No. 7 level in the Black Star orebody enabled the existence of a lode of copper ore of economic grade to be established. At the request of the Commonwealth Government of the day a programme of development for copper production was undertaken whilst lead smelting was continued as before the war.A series of flotation tests on up to 1,500 tons of ore at a time, was undertaken and the concentrate so obtained was stockpiled. These tests were conducted, using one section of the lead mill, and demonstrated that a concentrate grade of 22-23% Cu with a recovery of 80-85% might be expected.These recovery figures were afterwards much improved, and 93-95%was obtained before the close of smelting in 1946.

Jan 1, 1953

Airblast overpressure legislative limits can be extremely difficult to meet throughout Australia, which has by far the most stringent limits of any nation in the world. As the difficulty in meeting the limits is strongly dependent on the scale of mining, it is not surprising that the Australian coal mining industry is experiencing particular difficulties in meeting these limits. Eight full scale overburden blasts have been modelled with respect to overpressure impact for a strip coal mine, involving both dragline (cast) blasting and pre-strip (non-cast) blasting. Overpressure levels in the range 100 to 125 dBL have been measured at distances varying from 2.4 to 5.7 km, and modelling has successfully estimated both the amplitude and shape of overpressure waveforms to within an average of 1.2 dBL. Typical errors of prediction are around 0.6 dBL. This accuracy of prediction has been achieved by considering the impact of only the face holes, and the accuracy of prediction of both shape and amplitude suggests that it is these holes which dominate the environmental overpressure impact at distances in the range two to six kilometres, for cast and pre-strip blasting operations. Modelling has been based upon the Elemental Overpressure Wavelet proposed by Richards and Moore (2002), incorporating actual hole coordinates, actual delay timing, and assumed delay scatter statistics. The incorporation of delay scatter statistics has been particularly significant, and allows the determination of the range over which the peak overpressure levels are expected to vary. To date, modelling has considered only the use of conventional pyrotechnic delays, though simple adjustment to the scatter definition would allow estimation of overpressure levels, and their variability, with electronic delays.

Jan 1, 2004

By Blattner P

The Late Miocene gold-silver bearing epithermal system at Waihi has some close similarities in its paleo-thermal and -geochemical structure with modern, volcanic-hosted geothermal systems such as Ohaaki-Broadlands. At Waihi an extensive braided quartz vein system is enveloped by hydrothermally altered andesites with minor tuff breccias and tuffs. A main stage of vein filling consists of multiple phases of chalcedonic quartz and fine to medium grained quartz, which are accompanied by pyrite, sphalerite, galena, chalcopyrite and acanthite below the base of oxidation. Platy calcite is present locally. Fluid inclusion studies indicate that the main stage quartz was deposited at temperatures of 189¦-273¦C from dilute (T¦ of -0.1 to -1.0¦C) fluids that were locally boiling. Homogenisation temperature Th versus T. data points lie within the field enveloped by dilution and boiling/gas loss paths determined for the Ohaaki geothermal field, and indicates that the parent hydrothermal fluid for the Waihi epithermal system had a similar composition to that at Ohaaki, ie 0.2 wt% equiv NaCI and 3.3 wt% equiv CO2. The hydrothermal alteration mineralogy and the isotopic composition of vein calcite indicate that the hydrothermal fluid contained relatively high concentrations of CO 2' as at Ohaaki. Oxygen isotope analyses of main stage quartz range from 6.1 to 11.6 %o and of vein calcite from 2.29 to 9.4% . Calculated d8Ow.½ values for the hydrothermal fluid that deposited the main stage quartz range from - 2.0 to -5.7%c , with a trend to less negative values with depth. They are similar to those in the deep chloride fluid in active geothermal systems with a substantial fluid throughput. A high fluid throughput at Waihi system is also evident from the extensive high intensity hydrothermal alteration and large volume of quartz deposited in the vein system.

Jan 1, 1995

By N Akizawa, A Tamura, S Arai

"An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation. Reaction products between high-temperature hydrothermal solution/uppermost mantle peridotite or lowermost crustal gabbro have been reported along Wadi Fizh of the northern Oman ophiolite; they are named as ‘mantle diopsidite’ and ‘crustal diopsidite’ respectively (Figure 1).The mantle diopsidite contains Cr-rich minerals like chromite, Cr-rich diopside (<2.5 wt per cent Cr2O3) and Cr-bearing grossular (<7.0 wt per cent Cr2O3). The chromites are varied in shape in the mantle diopsidite, euhedral to anhedral chromite grains contain globular inclusions of grossular and chlorite, and film-like chromite veinlets branch off from partially dissolved coarse chromite grains. In the crustal diopsidite, fine chromite grains are included in oscillatory-zoned skeletal uvarovite, especially in its high-Cr zones. The uvarovites are rich in rare earth elements (REEs). Direct laser ablation – inductively coupled plasma – mass spectrometer (LA-ICP-MS) analysis of the primary fluid inclusions detected Na, but not K.Our detailed studies of Wadi Fizh diopsidites clarify that the high-temperature hydrothermal solution dissolves chromite grains at the uppermost mantle section and precipitates hydrothermal chromite at the lowermost crust section. In addition, REEs were mobilised in the hydrothermal solution together with Cr. The hydrothermal solution involved in the diopsidite formation is assumed to have been rich in NaCl, and could mobilise appreciable amounts of Cr and REE.CITATION:Akizawa, N, Arai, S and Tamura, A, 2015. Chromium and rare earth elements mobility by sodium-bearing high-temperature hydrothermal solution – an example from mantle diopsidite and crustal diopsidite, in Proceedings PACRIM 2015 Congress, pp 291–296 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Mar 18, 2015

By Andersen AK

As part of a research program sponsored by Continental Copper and Steel Industries, Inc. (cos), investigations have been conducted by the Colorado School of Mines Research Foundation, Inc. to study the effect of high current densities on electrolytic processes. The importance of high current densities has long been recognized, particularly in the deposition of copper, and the results of considerable research on the subject have been reported in recent years (19 29 39). This is not surprising because, besides plant capacity, current density is the other major factor which will determine the process economics. In the production of electrolytic copper, current efficiency, steam consumption, number of cells, building area, metal inventory, cathode purity, and power consumption are all affected by current density. The ability to maintain a high current efficiency and satisfactory cathode purity while increasing the current density to twice or three times that commonly practiced could result in considerable saving of capital investment and reduce the operating cost per ton of metal produced. The optimum current density i.e., that current density of which production cost would be at a minimum, can be established from an analysis of the various inter- relating factors (49 59). A review of.all operating electrolytic plants (electrowinning and electrorefining) will indicate that most of these plants are operating at 50% or less of the optimum current density (6). One of the reasons for not using the optimum current density may be attributed to the fact that conventional electrolytic tank- house equipment does not perform satisfactorily at high current density operations. Various investigators (19 79 8) have attempted to overcome this limitation by modifying the design of the electrolytic cell, virtually unchanged since it was first introduced in the late 1800's. Previously, these attempts have not resulted in,a cell design suitable for commercial application. However, recently, a cell has been designed which performs efficiently under such conditions. This is a CCS development (patents applied for).

Jan 1, 1969

By C M. Rebagliati, J G. Payne, K Roberts

The Pebble deposit, located in south-west Alaska, is one of the largest Copper- Gold-Molybdenum (Cu-Au-Mo) porphyry systems in the world, with a current resource of >8 billion tonnes which contain 73.7 billion pounds of copper, 87.1 million ounces of gold and 4.16 billion pounds of molybdenum. The Pebble deposit formed at ~90 Ma, during emplacement of subduction-related hornblende granodiorite porphyry intrusions emplaced into Jurassic-Cretaceous sedimentary, volcanic and subvolcanic intrusive rocks of the Kahiltna Terrane. The Pebble West and Pebble East Zones represent two thermal and fluid centres in a single large magmatic-hydrothermal system. The West Zone extends from surface to about 500 m depth, has thin zones of oxide and supergene mineralisation overlying hypogene chalcopyrite mineralisation, and is amenable to open pit extraction. The East Zone extends to at least 1700 m depth, is higher grade, occurs beneath an eastward-thickening cover of younger sedimentary and volcanic rocks, lacks oxide and supergene mineralisation, and is being evaluated for underground block-cave mining. Most Cu-Au-Mo was introduced with early K-silicate alteration and related quartz-sulfide veins. In the East Zone, a structurally-controlled overprint by advanced argillic alteration significantly increased Au and, to a lesser extent, Cu grades. Exploration potential at Pebble and its surrounding district remains high. Several other porphyry, skarn and epithermal deposits have been discovered in the district, but only limited exploration has been conducted. The eastern, higher grade part of the Pebble deposit remains open in several directions, with significant potential for resource expansion by ongoing, aggressive drill exploration. An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation.

Jan 1, 2008

Application of Agitated Leaching for Iron Removal from Silica Using Sulfuric and Hydrochloric Acid In this research, iron removal from silica used in glass industry was investigated using agitated leaching method. Silica sample was provided from silica concentrate originating from Chalchoog Silica Mine located in Abhar, Iran. The sample contained silica, iron oxides and clay minerals. For characterization of samples XRD and XRF analysis and atomic absorption method were applied. Silica and iron oxide (Fe2O3) grade of head sample was 98.41 per cent and 0.067 per cent respectively. Two inorganic acids (sulfuric and hydrochloric acid) were used in agitated leaching tests. Two series of L9 orthogonal array of Taguchi design with replication were used to determine the effect of parameters including acid dosage, leaching duration, ambient temperature and solid content on iron removal. The statistical calculations and analysis of variance (ANOVA) were carried out by means of DX7.0, Minitab14.0 and Winrobust1.02 softwares and also statistical calculations were checked manually using Excel software. Also multivariate regression was applied in order to forecast Fe2O3 conent of final product. The optimum conditions for leaching tests which sulfuric acid was employed are as follows: 40 minutes leaching time, temperature of 85¦C, 40 g/L acid concentration and solid content of 20 per cent. Under this condition the amount of iron oxide in silica was decreased to 0.042 per cent. The optimum conditions for leaching tests which hydrochloric acid was employed are as follows: 80 minutes leaching time, temperature of 75¦C, 30 g/L acid concentration and solid content of 20 per cent. Under this condition the amount of iron oxide in silica was decreased to 0.035 per cent.

Sep 13, 2010

The Myally Beds, Surprise Creek Beds and Mount Isa Group form the upper part of the Proterozoic Western succession of rocks in northwest Queensland. The latter two units are partly equivalent, and are important for their base metal content at Mount Isa and elsewhere. The arenaceous Myally Beds lie unconform- ably or disconformably below the Mount Isa Group and Surprise Creek Beds; they contain four mappable units which were deposited on a broad, shallow shelf washed by east-trending currents. Emergence of the Myally shelf initiated a series of parallel, possibly intra- cratonic, troughs to the east and west. In the east, the Surprise Creek Beds were deposited between the emergent shelf and base- ment rocks, and consist of a shelf and trough facies divisible into 7 and 10 units, respectively. Trough sediments are continuous north-south, and show turbidite character- istics; algal dolomite characterizes the shelf facies. To the west in the Mount Isa trough, an orthoquartzite facies, the Warrina Park Quartzite, defines the base of the Mount Isa Group. Hinge zones between the shelf and trough environments are marked by east-west facies changes, and provide a focus for later major north-south faulting. However, some penecon- temporaneous faulting near Mount Isa is best explained as complex post-depositional faulting of a disconformable sequence. Subsidence and deposition in the Mount Isa trough continued for a longer period than in the Surprise Creek trough, allowing accumulation of lead and zinc deposits in the upper half of the sequence. The Surprise Creek Beds appear equivalent to the lower half of the Mount Isa Group, and are probably not prospective for lead and zinc. Turquoise and possible other secondary copper minerals are widespread in the Warrina Park Quartzite and equivalents in the Surprise Creek Beds, and further investigation of these formations seems warranted.

Jan 1, 1974

The original leases making up today's North Kalgurli Mines were developed by independent companies on an ad hoc basis. The major disadvantage which now arises is the varying levels of mining horizons. From Kalgurli Shaft in the south, through main Shaft and to Croesus Shaft in the north, there are three separate sets of levels. work has commenced to link the three areas with either common levels or new development which will facilitate common access and haulage via Main Shaft.Generally, the workings at North Kalgurli were established at the turn of the century. The introduction of techniques and equipment to bring the mine into the 20th Century has been difficult and slow. The general size of openings, a widespread workforce and complex ore distribution often make innovation and change more than a challenge.

Jan 1, 1985

By Richards AB

This paper describes the ENVIB software system, which has been developed in a menu-driven form to aid in the monitoring and assess- ment of vibration caused by routine blasting operations and for research and development projects. The paper gives an outline of the capabilities of the system by means of screen-dumps and a general descriptive commentary. Technical notes have been added where appropriate to further describe the system. The ENVIB system covers: I . Analysis of blast vibration results, and preparation of graphs and tables for control and estimation purposes. 2. Effects of atmospheric conditions and air vibration propagation. 3. Real-time acquisition and analysis of analogue blast vibration sig- nals directly from transducer equipment or from FM tapes. 4. Analysis of digital files on floppy disc or transferred via the serial port from blast monitoring equipment. 5. Transfer function calculation for structure response studies.

Jan 1, 1988

By Roe P, Lowell A

This paper outlines software development and design work carried out by Mincom Pty Ltd in collaboration with Capricorn Coal Management (CAPCOAL) for computer based design of rehabilitated strip mine landforms at German Creek Mine. Current developments and future application areas for this software are also discussed in relation to other mines in Central Queensland. The development program was initiated in response to statutory requirements placed on mining companies in 1990 to produce a five year Plan of Operations which was to include a contour plan of the final rehabilitated mine landform at the end of the five year planning period. This plan was to be submitted to the Department of Resource Industries (DRI) by 1 December 1990. Due to the limited time given to prepare the plan, a work program was formulated in collaboration with Mincom Pty Ltd to develop suitable software to carry out the design work and provide the required plans and quantities. The software had to include computer based methods to allow design of the proposed landform in line with the rehabilitation strategy adopted by CAPCOAL at the time.

Jan 1, 1991

The preamble to the mining Act sets out that such Act is to provide for the encouragement and regulation of mining within the State of Queensland. This paper will attempt to follow the legislative path of such aim and in particular to show what part Mining Wardens play in the administration of the Mining Act.The Mining Act empowers the Governor in Council to constitute Mining Districts and Mining Fields and to appoint any duly qualified officer of the Public Service of Queensland to be a Warden or a Mining Registrar. As a matter of practice Stipendiary Magistrates who hold office in the major centre within a Mining District are appointed Wardens and Clerks of the Court are appointed Mining Registrars. In some districts where there is no Stipendiary Magistrate the Clerk of the Court is appointed an Acting Warden with all the powers of a Warden. Every Warden so appointed is a Warden for the whole State.To achieve impartiality Section 74 of the Mining Act provides that a Warden shall not hold or be entitled (directly or indirectly) to the benefits of any share or interest in a mining tenement or mining venture and provides a penalty of $1000 or imprisonment for six months or both, for contravention of such section.

Jan 1, 1986

Utah Development Company operates a mine at Blackwater with a present annual production of 4 000 000 tonnes of coking coal. Mineable seams outcropping on the company's lease are part of the Permian Mammoth Rangal Coal Measures. Current operations are based pre- dominantly on the Main Lower seam. Coal quality variations occur along the seam strike, in the direction of seam dip, within the seam plies and in isolated anomalous areas. Raw coal of non-specification quality is washed to reduce ash and sulphur and to improve the free swelling index. Raw coal meeting specification quality is sent directly to product, by-passing the washplant. Careful attention to mining, coal preparation and product blending is necessary to ensure that the combined product meets specifications.

Jan 1, 1974