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By Flloyd J. M

A continuous oxygen probe,incorporating a SIRO2 solid electrolyte oxygen sensor which measured the oxygen potential of a small volume of gas enclosed above the melt's surface,was constructed and tested. The oxygen potential of iron-silicate slags in equilibrium with solid iron in the temperature range 1250 to 1300¦C were measured continuously for tests of up to 40 hours duration. Results were in agreement with those of previous workers using gas equilibration techniques. Tests on non- iron buffered slags proved unsuccessful due to corrosion of the probe's component in contact with the slag and an alternative material is Required.

Jan 1, 1987

By A M. Ebbels, D Pratt

The current commodities super-cycle has seen an explosion in the number of mining projects demanding human resources throughout the world. The demand for key personnel currently far outweighs the international talent pool and will take several years to subside. A highly effective project team can be the difference between a successful project and a bad public relations exercise. Building an effective team and retaining the team members has become one of the major influencing factors for successful project development in the mining industry in the last decade.Increasingly, international teams are being established combining skill sets, subject matter experts, unique previous experiences and diverse cultures to deliver mining projects all around the world.This paper explores the characteristics of a highly effective team, the communication and geographic challenges and some potential pitfalls which influence the ability to form effective teams within the mining industry.CITATION:Ebbels, A M and Pratt, D, 2012. A great project team - Bringing together location and culture, in Proceedings Project Evaluation 2012 , pp 197-202 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 24, 2012

By H Kurth

High specification Prompt Gamma Neutron Activation Analysis (PGNAA) has been successfully applied to conveyed flows at iron ore operations since 2002 to representatively measure ore quality for improved quality management and process control. While the PGNAA technique has changed little since that time, significant improvements have been made in measurement capability. Elements previously unable to be measured well or at all using this technique are now measurable and one of these is phosphorus. Aluminium and magnesium are also key elements in addition to calcium and silicon in determining sinter basicity in ironmaking. Other elements measured routinely in iron ores include iron, carbon, potassium, sulfur and manganese. The benefits of representative measurement cannot be overstated as iron ore mining operations in South Africa, Europe, Australia, Asia and the Americas have discovered. The technology is applicable to any conveyed flow where elemental analysis in real time assists with quality management, from raw materials in ironmaking through to scrap steel in steelmaking and coal quality for coke-making. Major benefits are realised when raw material processing is optimised and this often includes diversion of material meeting a required quality so it can bypass unnecessary processing. This includes waste rock which can be diverted from a plant feed stream in 30 sec increments or ore that meets product quality being diverted to bypass beneficiation. Analysers are successfully utilised to identify ore types that assist with upgrade optimisation in jig plants; measuring feed, product and discard flows to also account for metal content. Product flows to stockpiles help manage production flows and stockpile qualities for different products and assist in blending ores into trains or ships to confirm specification compliance. Technologies can be used in magnetite processing but are predominantly used in hematite and goethite ore processing operations. The paper details examples of the above applications at various operational sites providing estimates of economic benefit as well as operational improvements.

Sep 18, 2023

By Gregg PEH, Stewart RB

Reclamation field trials commenced in 1985, two years before the granting of the Mining Licence. The level of pasture production on varying soil depths (0 cm, 5 cm, 15 cm and 25 cm) overlying both tailings and oxidised waste overburden was assessed. After seven years, the rate of increase of N, C, P and S, losses of S and P and pH changes were investigated on the plots where grass seed was sown into bare tailings. It was determined that on these plots it would take approximately 24 years to reach the original carbon and nitrogen levels at the mine site.

Jan 1, 1995

By O Dahl, I M. Platten, E J. Sides

Many narrow-vein gold deposits are characterised by a high to extreme nugget effect and the presence of coarse gold. They rank amongst the most difficult of deposits to produce an accurate and precise resource estimate. This contribution presents a case study from the Nalunaq Gold Mine in Southern Greenland. The mine commenced operation in May 2004 and is currently operating at a rate of 400 tonnes per day, to produce about 100 000 oz gold per annum from a total resource base of 1.2 Moz. Mineralisation is characterised by quartz veins that are hosted within a shear zone that is continuous over about 1000 m. The principal orebody is the Main Vein structure, which ranges up to 3 m in width, maintains an average dip of 35¦SE, and contains significant gold grades (1000s g/t Au). Gold particles are often visible, with 25 per cent being greater than 250 microns in size. Variography using underground development samples indicates a nugget effect of about 75 per cent. For the 2005 resource estimate, a 2D metal accumulation ordinary kriged block model was used to produce a global grade for the Target and South Blocks of the Main Vein. Grade control chip-channel samples are collected from æshantyÆ drive footwalls, and used as the basis for both the kriged block model and to determine the grade of individual stope blocks by peripheral weighted averages. Geology plays a key role in mining efficiency, given the locally variable nature of the ore zone.

Jan 1, 2006

By Schmincke H-U

The Pleistocene basanite-tephrite Rothenberg cone complex was built by an alter- nation of strombolian and phreatomagmatic phases of explosive eruption. Two main centres, on a one km long NNE-trending fissure, were active during its construction. The strombolian deposits from three discrete facies corresponding to the crater-fill and inner wall and outer wall environments on the cone. The outer wall facies consists of an alternation of 1. 'normal' coarse-grained, relatively well- sorted lapilli and bomb beds, and 2. finer-grained poorly-sorted lapilli beds. Evidence suggests that the former was pro- duced by open-vent lava fountaining, with balanced magma supply and discharge rates, and the latter are the products of eruptions during partial blockage of the vent, by collapse of wall-rock, and formation of a degassed crust on the magma. The resulting explosions there- fore ejected a mixture of fresh actively ves- iculating magma, older partially degassed lava and material recycled from the wall of the cones. The phreatomagmatic deposits are an alternation of moderately-sorted fall beds and thinner ash-rich pyroclastic surge and rain-flushed units. The clast populations are much more diverse than strombolian ones, including abundant wall rock fragments from 0-100 m depth. The juvenile (magmatic) particles range from highly vesicular scoria to dense 'bread-crusted' clasts, and contain abundant small wall rock inclusions. The phreatomagmatic phases are products of explosive interaction of small batches of magma with shallow groundwater. Vesiculation of this magma played a small but significant role throughout the fragmentation.

Jan 1, 1987

The Hodgkinson goldfield contains over 50 separate lodes which have produced 9.7 tonnes of gold from ore averaging 37 g/t. The gold-quartz.lodes are spatially separate from tin and base metal mineralisation, associated with Permo-Carboniferous granitoids in the province. Host rocks consist of sub-greenschist metamorphic grade shale, conglomerate, sandstone, spilite, chert and melange. Oreshoots average 100 x 30 x I m in Size and are contained in cross-cutting quartz. filled with steep-dipping shear zones. Mineralisation in the quartz. consists of gold with minor arsenopyrite, pyrite, galena, and sphalerite with rare calcite. Scheelite and stibnite are aSSOCIated locally but are not necessary proximal or coeval. Alteration is restricted to centimetre-scale phyllic selvedges adjacent to the veins and veinlets.Most of the lodes and vems occur within six main 1.5 x 0.25 km mineralised areas whIch may indIcate separate areas of fluid flow and precipitation. Ore controls differ m melange- and sandstone-hosted lodes but several features are common to all the oreshOOlS. Most of the lodes occur within zones of duauon that are caused by splaymg, refraction through carbonaceous shale-sandstone contacts, or by rolls and changes in strike and dip.Lithologic contacts may act as areas of permeability and chemistry contrast which focus fluid and precipitation. Tensional veins are common between parallel shear zones and curved spur veins occur both in the hangingwall and footwall of the main fissure. Intersections and contacts may have enhanced local fluid flow in many of the areas.

Jan 1, 1991

By Z W. Orndorff

Excavation through sulfidic geologic materials during construction activities has resulted in acid rock drainage (ARD) related problems at numerous (>40) locations across all five geologic regions of Virginia, USA. Potential acidities ranging from >100 to develop a statewide sulfidic materials risk map; document ARD impacts to soil and water quality and engineered structures; and develop methods to assess site-specific risk potentials within a given highway corridor. A statewide sulfidic materials GIS risk map was developed based upon the state digital geology map which assigned four levels of relative risk to all mapped strata based upon predicted lime requirements and probabilities of encountering highly reactive materials. Non-highway construction activities have also routinely disturbed sulfidic materials, and a recent airport project in northern Virginia resulted in over 150 ha of extremely acidic (pH 45 mg/L) run-off from this site heavily damaged a receiving stream, partially due to the fact that it dissolved the galvanised steel water control structures in stormwater detention basins, leading to direct discharge of run-off and sulfidic sediments. The airport area was treated and revegetated in 2002 with a combination of lime-stabilised biosolids, straw mulch, and acid-tolerant grasses. Water quality in a receiving second-order stream quickly responded to the treatment, but some release of N was also noted as a secondary effect. Collectively, these results point out the importance of accurately assessing the potential for excavation of sulfidic materials in construction environments, and the necessity of developing toxic materials handling strategies similar to those employed in mining environments.

Jan 1, 2003

Urban railway systems need high invest- ments, especially if their routes and stations have to be placed in the subsurface. In the FRG the construction and equipment cost of urban underground railway systems are in the range of 60 to 100 Mill DM per km tunnel. For this reason, track sections on the surface and on elevated structures are used as far as that is possible. Considering whole systems, the costs are in a range from to 45 Mill DM per km length for a metro system with about 80 % of its tracks and stations in tunnels and from 20 to 25 Mill DM per km for a light railway system with about 25 % subsurface infra= structure. The amount of route lengths in tunnels depends on the size of a city, the situation regarding above ground structure and free space on the surface, the level of service quality which has to be achieved with the railway system etc. Despite of the urgent needs to improve the transport conditions there very often arise doubts if an urban railway system is really necessary and can be justified in an economic sense. The experience from many cities around the world shows, that there arise a lot of benefits from urban railway systems, especially with larger sections placed under- ground. They are to be found in the interests of the operator (f.e. operating costs), the user (travel time, quality of service etc.) and regarding social aspects (environmental protection, accidents, consumption of energy Etc.).

Jan 1, 1987

By G W. Wilson, C Panidis

Potentially acid forming (PAF) waste rock contained in dumps formed as a result of open cut mining of metalliferous orebodies are conventionally sealed or covered using a near-saturated, low permeability compacted clay layer, protected with a mulch layer and/or vegetated growth medium. The purpose of the compacted clay layer is to limit oxygen diffusion and the infiltration of rainfall into the dump. Where the aerial extent of the PAF waste rock dump is large, or where suitable clayey material is in short supply, it may be difficult to source sufficient suitable clayey material to form the cover. The paper describes a laboratory-based investigation of combining inert waste rock and tailings to form an alternative seal or cover material. The inert waste rock was sourced from the trafficked surface of a non-acid forming (NAF) waste rock dump, with a maximum particle size of about 100 mm. This was combined with NAF thickener underflow tailings slurry in various mass ratios, and the resulting mixtures tested for their particle size distribution, compaction characteristics, soil water characteristics (relationship between suction and volumetric moisture content), and saturated hydraulic conductivity. The mixtures tested ranged in consistency from those dry enough to be compactable, to those with the consistency of wet concrete that lend themselves to placement without the need for compaction. The laboratory test results showed that the suitability of the mixtures as seal or cover materials is very dependent on the particle size distribution of the mixture, with well-graded mixtures having substantial fines performing best.

Jan 1, 2003

By A H. Hofstra, G P. Landis, P Emsbo, A G. Hunt

Models of the evolution of the hydrothermal systems that form porphyry Cu (Mo-Au) deposits are compromised because aqueous magma-derived fluids in the ore zones of most deposits have changed from their original magmatic compositions as a result of cooling, depressurising, mineral precipitation, brine-vapour unmixing and fluid-rock reactions. However, in deep quartz-rich, sulfide-poor veins from numerous porphyry type deposits, we have identified parental fluids trapped in inclusions at near magmatic temperatures and pressures above the brine-vapour unmixing solvus. We have analysed these inclusions for bulk salinity, density, solute chemistry, helium isotopic ratios and elemental composition. These parental inclusions contain 35 - 70 volume per cent bubble, are low to moderate salinity, contain up to ten mol per cent CO2, and commonly contain a chalcopyrite daughter crystal. Our results indicate that these Cu-rich fluids transport Cu from a plutonic complex below upward into a hydrothermal system, where decompression, cooling, unmixing and water-rock reaction drive ore-mineral precipitation. Na/Cl ratios greater than one indicate that in addition to chlorine, sulfur and/or carbonate must play a key role in Cu transportation. Helium isotope ratios indicate that between ~15 and 100 per cent of helium in these fluids is mantle-derived. We suggest that in addition to He, volatiles from mafic magmas in the mantle are also likely to supply CO2, Cu and S to the fluids that form porphyry copper deposits. An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation.

Jan 1, 2008

Information from bores in the LatTobe Valley has been accumulating for over fifty years, and the manual extraction of details has become a limiting factor in their use.Punched card equipment, installed by the State Electricity Commission for accounting purposes, was known to be available for reasonable periods, and it was suggested that this could help in the extraction of data from the voluminous records.Investigation showed that they could be substantially duplicated on cards, with consequent gains on many operations; the cards being regarded as an auxiliary to the existing records.BRIEF DESCRIPTION OF RECORDSAs a bore is drilled a continuous record of the strata is kept, together with notes on the presence of water or any unusual features which the driller may observe.When coal is struck, samples of each ten feet are usually sent for analysis.The location and surface level of each bore is fixed by surveyors, and details of dates and methods of drilling are also kept.Bores are allocated numbers, prefixed by the name of the parish within which they are drilled. Numbers are allocated in conjunction with the Department of Mines, to avoid duplication.Records of strata and analyses are kept in folders, with 100 bore numbers per folder.Standard plans are drawn, showing the locations, bore numbers and surface levels. For each bore they also show the depth and thickness of coal struck, and the total depth drilled.Cross sections are then drawn, connecting the various coal seams, which have been identified by the geologist.

Jan 1, 1960

By X Z. Sun, N Jiang, J H. Zhao, C X. Wang, L Y. Bai

In backfill grouting for underground coalmines, the filling materials strengthen the caving rock and support the overlying strata to reduce surface subsidence. The broken roof strata fail and collapse during mining operations without appropriate supporting measures being taken. It is difficult to perform continuous backfill mining on the working face of such roofs using the existing mining technology. Therefore, in order to solve the above problems, fly ash and mine water are considered as filling materials, and flow characteristics of fly-ash slurry are investigated through laboratory experiments and theoretical analyses. Laws governing the diffusion of fly-ash slurry in the void of caving rock masses and in the void between a caving rock mass and a basic roof are obtained and verified. Based on the results obtained from the above analyses and field conditions at the Zhaoguan coalmine, Shandong Province, China, a cave backfill grouting system of the hauling pipeline is developed and successfully tested at the 1703 working face. The results demonstrate that a filling rate of 43.46 per cent is achieved, and the surface subsidence coefficient of the grouting process is found to be 0.475. Compared to the total caving method, the proposed system is found to achieve a reduction rate of 40.63 per cent. This effectively helps in lowering the value of the surface subsidence coefficient. Fly ash and mine water, considered as primary materials in this study, also play a significant role in improving the air quality and water environment.

Nov 29, 2022

Multiple regression analysis applied to ventilation records of stopes on the Witwatersrand showed that it was possible to estimate the temperature increase per 100 ft for a new stope with a standard deviation of 0' 5°F. The analysis also threw light on the relative effect on this estimate of five different factors.Application of the analysis of variance technique to a factorialexperiment on the production of dust during rock drilling showed that the effects of air and water pressure were quite small but also showed that the between-machine variation was unexpectedly large.Analysis of variance also proved a valuable means for assessing the bias and random error variation of aneroid barometers used in pressure surveys.INTRODUCTIONThree examples are discussed to illustrate the use of the techniques of "analysis of variance" and "multiple regression" in research on the ventilation of gold mines. Although the techniques are basically similar their application to each example has a slightly different emphasis and the examples were chosen for this reason. The variation ofemphasis is as follows.1. Temperature increases in stapes. This work was undertaken as a preliminary to possible extensive controlled experimentation (Lambrechts, 1959). Data collected in routine work by the mine ventilation personnel were used for analysis and no specific experiments were carried out. The main object was to see whether such data could provide any strong pointers to factors which might be worthy ofmore careful study and to factors which could initially be ignored. Of course, there was hope that the study might provide an empirical formula for rough forecasts.

Jan 1, 1962

By A. W. CAMERON

Over a 4 hr period of steady plant operation samples were taken at regular intervals from points within the grinding and flotation circuits. Size fractions of each composite sample were analysed for lead and zinc values and a comparison made of the behaviour of the lead, zinc, and gangue minerals, size by size throughout the whole circuit.Analysis of the breakage behaviour using dynamic mathematical models gave the rates of breakage of each size fraction of each main component. Simulated grinding experiments showed that the main grinding circuit had some reserve capacity.In the lead flotation circuit all lead values between 150 mesh (Tyler) and 5 microns had excellent flotation characteristics, and a major proportion had a high rate of flotation which was practically the same for all sizes. Increase in overall lead recovery would require improvement of the flotation behaviour of ultra-fine lead minerals. These were slow floating and were responsible for approximately half the lead losses in the final zinc concentrate and one-third of the lead losses in the final tails.All sizes of zinc values between 100 mesh and 7 microns floated well and the performance of the zinc flotation circuit was mainly limited by the relatively poor flotation of the very fine zinc values. Approximately 60 per cent of the zinc lost to the final tails lay within the minus 7 micron fraction.The overall flotation conditions were conducive to very good selective flotation of the major proportion of the values and limitations in metallurgical performance were mainly due to the properties of the ultra-fines.

Jan 1, 1971

By Y H. Zhu, X X. Tang, Y C. Yin, M L. Xing

Based on the stiffness theory, the stiffness difference and energy supply of surrounding rocks are important inducing factors for strain burst. However, due to the lack of multi-level low stiffness testing machine, there are few experimental studies on rock failure mechanisms under the influence of loading stiffness. This paper introduced a self-developed rock testing system with changeable stiffness. The main testing machine of this system is a combined structure of inner and outer frame. The change in the loading stiffness is achieved by using a stiffness servo control system to control the energy accumulation in the inner frame. The tests of the sandstone specimens under three different loading stiffnesses in the testing system showed that the loading stiffness did not significantly affect either the uniaxial compressive strength or the Young’s modulus of the rock. However, the post-peak stress-strain curve of the rock became smoother and steeper when the loading stiffness was decreased, and the stress drop rate increased. It is shown that the stress drop rate had a power function correlation with the loading stiffness. After the peak load, the inner frame of the testing system rebounded several times at high speeds. The magnitude of the instantaneous rebound speed and the rebound duration increased with the decrease of loading stiffness. Both the mean rebound velocity and the total rebound deformation had power function correlations with the loading stiffness. The loading stiffness has limited effect on the energy storage and energy dissipation characteristics of the specimen, while the released energy of the testing machine increases as the loading stiffness decreases, which is the key factor affecting the failure mode of the specimen. According to the test results, a rock burst mechanical model considering the stiffness is established, and the energy supply mechanism of rock burst is quantitatively explained.

Nov 29, 2022

By Madgwick J

A novel method for determining viable cells of the mineral leaching bacterium Thiobacillus ferrooxidans has been developed. The cells were collected on 0.45/Lm cellulose acetate filters, washed with artificial minewater, and incubated in the presence of ferrous ion at pH3 in an atmosphere containing radioactive (14C) carbon dioxide. Colonies of bacterial growth were detected by the image formed on X-ray photographic paper (autoradiography). The method was compared with three conventional techniques and shown to detect three orders of magnitude more cells in cultures of Thiobacillus ferrooxidans in the late exponential phase of growth.

Jan 1, 1987

By M Jahani, M Taji

For suitable production planning in an open pit mine, and also to carry out the optimisation process during the mining production cycle, prediction of fragment size distribution is required prior to carrying out the blasting operation. For this purpose, many prediction models, such as empirical models, were presented. The proficiency of these models differs in various conditions and mines. Therefore, in this paper the most important models, including SveDeFo, Kuz-Ram, CZM, Modified Kuz-Ram in 2005, Kuznestsov-Cunningham-Ouchterlony (KCO) and also Gheibie et al, were examined by the information of 20 blasts in Gol-Gohar iron ore mine. Fourteen images were taken on average for each blast. For image processing analysis Split-Desktop software was used. After examination, it was understood that none of the available empirical fragmentation models had presented acceptable performance, except the Kuz-Ram model for magnetite ore, which had somewhat acceptable results. However, this model for blasting patterns in hematite presented unsuitable results. Examination and comparison of two important distribution functions, Rosin-Rammler and Swebrec, were carried out and it was observed that the performance of Swebrec for fines was far better than Rosin-Rammler. This result for the upper part of fragment size distribution curve, coarse, is the reverse.CITATION:Jahani, M and Taji, M, 2015. Comparison of empirical fragmentation models at the Gol-Gohar iron ore mine, in Proceedings 11th International Symposium on Rock Fragmentation by Blasting, pp 707–714 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 24, 2015

Until 1937, the mining of ore was carried out by conventional methods, using pneumatic drills and standard drill steel. The adoption of the diamond drill, formerly used for exploration work, for blast hole drilling in stopes, was first developed by Noranda Mines Limited, Noranda, Quebec, although it had been used previously in Northern Ontario and Western United States, to remove weak pillars and ore remnants left by conventional methods. Previous to the adoption of the diamond drill method at Noranda, a sub-level benching system of stoping was used. Sub-levels were driven at 35 ft. intervals and the benches drilled off by pneumatic drills using sectional steel. Results were very satisfactory, in sulphide ore, where the drilling was comparatively easy, but in the harder rhyolitestopes the footage drilled per machine-shift was only half of that obtained in the sulphide stopes, and owing to the high gauge loss, there was often difficulty in drilling holes to the required depth. This led to trials with the diamond drill for this type of work. While the cost per foot was more than with sectional steel, an appreciable saving in development work could be made by increasing the sublevel interval from 35 ft. to 60 ft., and stope widths from 60 to 100 ft. This saving, together with the increase in blasting efficiency, resulted in a substantial reduction in overall costs.CONDITIONS FOR SUCCESSFUL APPLICATIONWhile long diamond drill blast-hole mining has widespread application, there are certain conditions which appear to be desirable, if not absolutely necessary, for its successful use.

Jan 1, 1946

By R Shaw, T T. Neidel, C Adams

Sampling equipment manufacturers endeavour to ensure that the mechanical equipment installed in sampling systems are designed and manufactured to adhere to the requirements of the International Organization for Standardization (ISO) or other standards relevant to the application. The mechanical parameters necessary to achieve these standards can be well controlled and requirements such as constant speed can be met through good mechanical design and engineering. However, when the equipment is installed and put into operation, the ISO compliance of the system is out of the hands of the equipment manufacturer and handed to the operator, who may be a generalist control system integrator.Making a sampling system perform according to standards, and being able to monitor and report on compliance require that the sampling system knowledge and the control integration is combined and applied in an integrated approach. Using a dedicated library of control routines developed for sampling can change a system from having compliant equipment to being a compliant system. The library has to include monitoring of relevant parameters and control and reporting on sampling parameters.CITATION:Neidel, T T, Adams, C and Shaw, R, 2014. Control and monitoring of International Organization for Standardization compliance for industrial sampling systems, in Proceedings Sampling 2014 , pp 121–126 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 29, 2014