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By Weller KR, Restarick CJ, Stewart PSB

Following a detailed assessment of concen trator performance at Broken Hill South Limited which was reported in a previous paper, the fine grinding section was changed from a parallel arrangement of the two grinding circuits to a series arrangement, and the concentrator per- formance re-assessed. The change to series grinding had virtually no effect on the actual or potential capacity of the circuit to make a final product with 80% passing 100 mesh. However, the fresh flotation feed contained significantly less +150 mesh lead and +65 mesh zinc (material which was shown to float poorly), without an increase in the quantity of poor-floating ultra-fine lead and zinc. From the size-by-size flotation recovery data, it was shown that overall recoveries of both lead and zinc were approximately 1% higher than they would have been without this change in size distribution and it was concluded that this was a direct result of the change in grind- ing procedure.

Jan 1, 1972

The Quiruvilca district, located 80 km east of Trujillo in north central Peru (Fig. 1), has produced over eight million tons of Cu-Pb- Zn-Ag ore from approximately 60 veins since 1789. "Quiruvilca means "sacred tooth" in Quechua, the lingua franca of the Incas. The expression refers to a prominent volcanic neck exposed several kilometers northeast of the district. The district covers an area of approx- imately 24 km2. The mines occupy the eastern quarter; workings underlie 6.7 km2 with a developed vertical range of 280 m. All pres- ently operating workings are owned by Corpora- cion Minera Nor Peru S.A., a subsidiary of ASARCO Incorporated. The oldest rocks in the area are Lower Cretaceous clastic sedimentary rocks exposed 7 km to the east. Lithologies include sand- stone, siltstone, shale, coal seams, and carbonates (Cossio, 1964). These rocks were folded and affected by regional low-grade metamorphism during the early Tertiary, 40-65 m.y. (Hollister, 1977).

Jan 1, 1987

By Quast K. B

Samples of limestone and micaceous hematite have been ground in a laboratory batch mill using equal weights of either rods or balls. Values of the Schuhmann distribution modulus, a, have been shown to depend on grind time and do not remain constant as often reported. The linear reduction in a with grind time was attributed to a change in grinding mechanisms with time. The product sizing from ball milling limestone showed a bimodal distribution, but rod milling produced a unimodal size distribution. The product sizing from milling micaceous hematite was difficult to interpret due to the major influence of the shape factor on the transition from screen sizing to cyclosizing.

Jan 1, 1995

By A van As

This paper serves to outline the circumstances and causes of the air-blast that occurred at Northparkes Mines in November 1999. It describes the design of the mine, the geotechnical issues surrounding cave propagation and the cave monitoring systems that were in place prior to the event. A short description of the air-blast that followed a sudden collapse is given. Details of the risk assessment process that evolved during the rectification process are provided with their subsequent modification to form the core of a major hazard monitoring process. The system is in line with the recommendations given by the Coroner resulting from the inquest into the deaths of the four people who lost their lives during the air-blast.

Jan 1, 2005

By Knijnikov M, Cameron D

Coal Quality management and the control of the flow of coal through complex mining preparation and transport phases of standard mining operations has assumed greater importance over recent years.

Jan 1, 1998

The industrial practice of separating finely' around valuable minerals from associ- ated gangue materials by froth flotation is well known. Despite the obvious importance of this industrial process, the predictive tools for plant engineering evaluation of flotation process variable changes are still in a developmental stage. Consider, for example, the situation where an operating engineer is faced with evaluating a change in an existing chemical reagent scheme, possibly based on batch laboratory data. When all is said and done, the engineer must still perform detailed physical testing of the proposed reagent change on the actual equipment in plant use to be confident even of the direc- tion of change of plant results, let alone the economic viability of the change. The theory behind chemical reagent behaviour in froth flotation has been studied extensively, e.g., (Aplan {1980}, Fuerstenau {1976}, Fuerstenau {1962}, and Somasundaran {1980}), and, certainly, important progress has been made. Unfortunately, the nature of the flotation process, with its complicated heterogeneous surface chemisty activity operating on highly variable and difficut to characterize ore surfaces, coupled with com- plex mass and momentum transfer phenomena, :;l riously compromises the plant scale predictive capability of theoretically based models.

Jan 1, 1978

Surface and near surface particulate gold occurs sporadically over an area of some60 km2 between Vunda and Navilawa on the west coast of Viti Levu, Fiji.Background grades of 0.01 ppm can be found in the zone of weathering from 3 to ZQm but, at Vunda, attain significance within certain "localities" ranging from 1000 m2 to 35000 m2 in area. Intense and deep weathering renders geological interpretation difficult but the higher grades seem to relate to equally weathered dykes and apophyses which intrude the tuffaceous country rock.Both country rock (5.4 m.y.) and intru-sives (4.8 m.y.) are of shoshonitic composi-tion and all rocks are consanguineous. At Navilawa, on the eastern end of the zone, basic monzonite crops out as a sizeable stock carrying low grade porphyry-type copper and gold. Between Navilawa and Vunda intrusives are as large apophyses and dyke swarms, and at Vunda, on the western end, only the upper ends of dykes and small apophyses are exposed carry-ing various sulphides, magnetite and rutilein hair line fractures. The level of erosion is thus deeper to the east and shallower to-ward tha wPst_

Jan 1, 1984

The addition of a thallous salt to the cyanide leach of a calcined pyritic concentrate causes a marked increase in the"rate of extraction of gold. This probably is due to the activation of passive gold by.th,e. thallous ions'.''Lea'd, bismuth, and mercury salts, which should produce ' a, similai effect, fail to do so. It is postulated that'this latter result, together with'the reprecipitation of silver at low cyanide levels, is due to the presence of soluble sulphide. The use of thallous salts to reduce leaching time is discussed briefly.

Jan 1, 1964

This paper describes operational experience with seam gas and spontaneous combustion management, gained during ten years of production history (1993 to 2003) in the Wynn seam at Dartbrook Coal mine. In addition, comparisons are made with more recent operational experience in the overlying Kayuga seam. Development and retreat longwall operations were undertaken in a 4.0 m thick working section of the Wynn seam, contained within the lower quarter of a circa 24 m thick mega seam, from 1993 until mining operations were relocated to the overlying Kayuga seam in 2004. Production from the first block of the Kayuga seam is currently underway with seam gas and spontaneous combustion management requirements being refined as further operational experience is gained. Seam gas management techniques, including pre-drainage with pressurised fracturing, surface to underground goaf drainage of a carbon dioxide rich seam gas and novel, high capacity ventilation circuits, were employed in the Wynn seam. Ventilation strategies included operating up to carbon dioxide STEL concentrations of 3.0 per cent in segregated return airways rather than being limited to the TWA-TLV concentration of 1.25 per cent. The spontaneous combustion experience at Dartbrook Coal has, to some degree, resulted in a change in the way the risk is managed in Australian coal mines. Values of carbon monoxide make and hydrogen concentrations are profoundly different from previously recommended management plan trigger levels and those used elsewhere in the industry. However, the detection of higher hydrocarbons together with rising oxygen depletion ratios and absolute hydrogen concentrations remain as indicators of advancing spontaneous combustion events. In this respect, experience gained in the Wynn seam was important in the initial management of the shallower Kayuga seam, an essentially greenfield site with no prior operational experience being available.

Jan 1, 2005

By Hayba DO

Metal-rich slurries discharged from excess-enthalpy geothermal wells at Kawerau (NZ) indicate that an efficient ore precipitation mechanism operates in some feedzones. In our conceptual model, which takes into account the relative permeabilities of liquid and gas phases in boiling fluids, a metal-precipitating liquid phase is effectively immobilised along boiling fronts, leading to the formation of highly concentrated ore. Chemical equilibrium and heat/mass transport modeling demonstrate the general applicability of this conceptual model to hydrothermal eruption environments.

Jan 1, 1995

By L Keeney

Cu-Au porphyry deposits are large tonnage low-grade resources dependent on processing large volumes of material. The ability to understand and predict comminution performance is critical, as it is frequently the rate-limiting step during processing. Parameters required from geometallurgical mapping and modelling of comminution performance are: A×b processing domains based on impact breakage variability, and BMWi processing domains showing grind response variability which lead to Mine throughput domains for a specific comminution circuit configuration. Due to the cost and/or large sample requirements of traditional comminution tests, insufficient data density and distribution of comminution indices commonly exist, making it difficult to model and map deposit scale variability. One method routinely applied to three dimensional domaining is to have an a priori zoning based on geological features (lithology, alteration, mineralogy, textures), and then apply to all material within a given domain the metallurgical values measured on a single sample or average of samples from that domain. The problem with this approach is that commonly the geological domains do not reflect comminution response, therefore compromising the quality of the average domain estimate. To resolve this problem an alternate integrated geometallurgical mapping and modelling method is applied to model and map comminution performance at Cadia East. This paper uses a data set of ~32 000 assay measurements and geological logging information, integrated with ~150 comminution measurements to analyse and develop proxy support models for comminution indices (ie A×b, BMWi, and throughput) based on inherent geological variability. Discrete downhole comminution processing domains are created, mapping orebody response while maintaining inherent variability.

Sep 5, 2011

By Klinefelter G

The United States Steel Mining Co., Inc. recently experienced a major mine fire at the Cumberland Mine. This mine is located in Greene County, Pennsylvania, U.S.A. and is mining a high volatile bituminous coal seam (Pittsburgh Seam). The mine fire was success- fully controlled and extinguished without loss of life or serious injury to any miner or mine rescue personnel and finally reopened within 40 days of its inception.

Jan 1, 1988

By Hanes J

More than 200 bursts in coal occurred at Leichhardt Colliery prior to December 1978 during mine development in the 6 m thick Gemini seam at depths approximating 400 m. Three large bursts each displaced more than 300 tonnes of coal and stone. Two of these which occurred in continuous miner developments, are described and compared. Geological settings, mining strains including induced cleavage and roof failures associated with bursts are described. A shotfiring technique replaced mechanised mining following a major incident at the colliery. Present mining procedures, the apparent improvement in stability of workings and ongoing geotechnical monitoring programme are discussed.

Jan 1, 1980

Towards Improved Hydrocyclone Models - Contributions from Computational Fluid Dynamics

Sep 13, 2010

By Nickelsen J, Theisen KG, Hansen PH

The use of stationary calciners in the processing of aluminium hydroxide has emphas- ized the importance of Bayer hydrate properties with respect to particle breakdown during calcination and subsequent treatment. Test results from calcination of several Bayer hydrates to sandy alumina in the FLS Gas Suspension Calciner (GSC) were obtained in a 250 kg/h pilot plant unit. Particle breakdown during calcination was influenced by content of solid sodium oxalate, trapped in the hydrate particles and operating gas velocities. Owing to the design and operational principles of the GSC it is possible to reduce particle breakdown to at least the same as what is found in long rotary kilns. Other major advantages reviewed are obtained through simplifications in plant design and operation, pointing to low specific power and heat consumption, and generally low production costs, thereby providing an attractive alternative to fluid-bed calciners.

Jan 1, 1981

By Sheer T. J, Van Rensburg J P

The primary objective of this research was to address the demands imposed on self- contained self-rescuer (SCSR) performance dur- ing simulated escapes. The results clearly indicate that SCSR performance, apart from the inherent technological features, is a function primarily of the physical and anthro- pometric features of the wearer, and of the particular nature of the escape route. These factors consequently play a major role in the planning of any escape strategy, which may vary from mine to mine. It is therefore concluded that each mine would have to formulate its own escape strategy which in turn would depend on the choice of SCSR, and the particular escape Route.

Jan 1, 1988

Average annual growth in consumption of primary energy in Australia over the past ten years has been 5.5% compared to a world average of 4.1%. Over the next ten years growth rate is expected to increase to 6% per annum due largely to the rapid development in the mineral processing industry. By the end of the 1970's natural gas is expected to supply more than 9% of Australia's, primary energy market. Coal will supply 40% and petroleum products 47%. Nuclear energy will make its appearance but-will only make a small contribution in the period. Australia has adequate reserves of natural gas and coal to supply its needs in the 1970's and beyond. However the newly developed reserves of crude, while supplying 60-70% of requirements-in the initial years; will need regular and sizable additions if they are to .keep pace with the expanding consumption. For Australia to become self sufficient in the period 1970-1990 it is estimated *that new discoveries-will need to approximate. ten times the volume of recoverable reserves found in Australia to date. .

Jan 1, 1970

This paper outlines the thermodynamic and mass balance principles which affect the distribution of cobalt between matte and slag during the pyrometallurgical treatment of nickel - copper sulphides and considers the implications with regard to maximising the recovery of cobalt from the smelting and converting circuit.

Jan 1, 1992

In late 1984, Council of the Australasian Institute of Mining and Metallurgy accepted a proposal to establish a Mineral Heritage Committee. This was to be involved in matters relating to mineral heritage-its recording, its preservation, and the acknowledgement that it can be of use to the mineral industry in the future. The Committee was established to ensure that all of the disciplines of our profession were included and that, so far as possible, all of our country as well as those countries of the Southwest Pacific Basin were represented. Some work has been commenced to bring real- isation of the importance of the heritage of our mineral industry to the forefront of the commu- nity's interest. There is not a state in this country and the Southwest Pacific where the mineral industry has not at various times proved to be the basis of community development.

Jan 1, 1987

The Big Bend and Cobra molybdenum prospects which occur near the margin of the Karamea Batholith in the Northwest Nelson molybdenum province are compared. The Big Bend Prospect is a 3000 m by 800 m area of disseminated pyrite and anomalous molybdenum associated with Cretaceous porphyry intrusives and later argillic and potassic alteration within Ordovician schists and phyllites adjacent to the batholith margin. The Cobra Prospect is a 1200 m by 1200 m area of weakly disseminated pyrite mineralisation and anomalous molybdenum-in-rock associated with moderate to strong quartz-molybdenite and quartz-orthoclase-molybdenite veining in quartzite.

Jan 1, 1979