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By I Sherrell, R Jain

Worldwide iron ore feed grades are trending downwards and will continue to do so with the increasing difficulties of upgrading ores. This has led to operations looking for ways to capture current tailings that still contain valuable material. In the past, these were acceptable to dispose of, but this practice is no longer economically feasible. With the increasing trend of re-mining previous tailings deposits that could be decades old, new equipment designs have been introduced to upgrade current or historic beneficiation plants. These designs can effectively upgrade these tailings to saleable products.Outotec conducted test programs for upgrading iron ore tailings from flotation rejects, thickener underflow or tailings dumps on samples provided by customers around the globe. The studies utilised Outotec’s SLon vertically pulsating high-gradient magnetic separator in combination with preprocessing equipment such as low-intensity magnetic separation, screen or scrubber and flotation for downstream processing of the magnetic concentrate. A review of the equipment required to economically process these tailings is provided, along with testing data and industrial implementation examples. The effect of different operational and design parameters on Fe grade and recovery from processing each tailings sample has been highlighted.CITATION:Jain, R and Sherrell, I, 2015. Iron ore tailings reprocessing to maximise ore production, in Proceedings Iron Ore 2015, pp 149–158 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 13, 2015

By J Morton

The Resource Management Act 1991 represented an innovative and unique piece of planning and environmental legislation when it was introduced. Since the Act was passed into law in 1991 it has been subject to nine amendments, many of which were of the ætinkerÆ variety. These amendments recognise that the Act has not been as successful in providing the æone-stop shopÆ for resource users that the Act was hoped to be. The latest and most significant attempt at changing the Act was the Resource Management Amendment Act 2003. The amendments made by the Amendment Act have proved to be largely unsuccessful in achieving any significant changes to the way resources are managed in New Zealand, and have failed to address many of the concerns which drove the original Resource Management Amendment Bill in 1999. The recent decision to discontinue further investment in Project Aqua has once again placed the Act in the spotlight as a significant hand-brake on major projects. This particular event has led to yet another review to be undertaken this year. The review will focus on five key areas:   1.   achieving the right balance of national and local interests; 2.   improving the design and process for local policy formulation; 3.   improving the consent decision making process; 4.   allocation of natural resources (water, air and geothermal); and 5.   supporting measures for building capacity and promoting best practice and implementation at the local authority level.  It is important for the business community and the mining industry in particular to seize the opportunity that this review provides to make sure that any amendments undertaken as a result of the review achieve the aims listed above. The review needs to be considered in light of the current regime for the management of natural resources in New Zealand. In addition to the Resource Management Act 1991, the Crown Minerals Act 1991 and the Building Act 1991, which form the core resource statutes in New Zealand, there have been other developments affecting the regime. Special legislation over and above the Resource Management Act 1991 has been enacted to protect the Hauraki Gulf and special legislation is currently being considered to protect the Waitakere Ranges in Auckland. In the Hauraki District mining is prohibited in some areas and a plan change mechanism is specified as the appropriate tool to use in the event a mineral resource is to be developed in those areas. The current review is a further opportunity to remedy the inadequacies of the Act.

Jan 1, 2004

By C Garlick, O Gregory, H Rogers, B I. Winters, Z C. Ye

BHP New Zealand Steel produces iron from titaniferous ironsand by a direct reduction process comprising multihearth furnaces/rotary kilns/electric iron melters. The electric iron melter is a six-in-line rectangular submerged-arc furnace which takes the partially reduced ironsand (80 per cent metallisation) from the rotary kiln and completes the reduction process to produce iron of nominally three per cent carbon. As the melter operates at around 1500¦C and under very hostile conditions, it is near-impossible to obtain any basic operating parameters such as the velocity and temperature distribution in the slag and in the molten iron. As a first attempt to understand the operating conditions inside the melter, a scaled room-temperature model using wax and water to represent the slag and iron, was constructed. This paper will report on some of the preliminary model results on the temperature distribution.

Jan 1, 1995

By M Stewart

Alluvial gold deposits in the area studied are preserved on the valley floor and elevated terraces due to a sequence of glacial/interglacial events during Pleistocene and Recent times. Continued regional uplift has overprinted these events. Prospecting by drilling and bulk sampling has demonstrated a complex alluvial gold resource which is now being mined.

Jan 1, 1989

By R Justa Cámara, L M. Pinillos Lorenzana

Barcelona Metro Line 9 (Line 9) is an essential infrastructure, improving the transversal transport in Barcelona by connecting the greater part of the currently existing radial lines. The purpose of Line 9 is to create a peripheral line surrounding the city of 1.6 million people (metropolitan area exceeds five million), and includes 52 stations, of which a total of 32 are deep shafts and 19 transfer stations in a densely populated area with several geographical constraints.The tunnel has an inner diameter of 10.90 m, bored with an earth pressure balance (EPB) tunnel boring machine (TBM) in soil sections with precast concrete lining type universal ring and segments 40 cm thick.A single tunnel solution was adopted, driven by functionality and costs savings. The internal tunnel section is divided into two levels to allow for one way rail transit including the platforms in each station on each level in order to optimise the space created by the TBM excavation and comply with the operational needs. The division in two areas of the tunnel was carried out through the construction of a horizontal slab resting on the tunnel segments with a constant thickness of 40 cm at the central part of the slab and supporting side walls.CITATION:Justa Cámara, R and Pinillos Lorenzana, L M, 2014. Two transit levels in one tunnel tube – an innovation in Barcelona Metro Line 9, in Proceedings 15th Australasian Tunnelling Conference 2014 , pp 387–398 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 17, 2014

By A K. Raina, V M. S R Murthy

Rock mass response in blasting is an important element to determine the performance of a blast along with its other outcomes. The near-field monitoring for rock mass response analysis is vital for determining the behaviour of a blast; however, due to costly and cumbersome methods involved in such measurements the subject has received scant attention so far and the publications on this account are perfunctory in nature. This paper presents a non-destructive method to monitor the blast-induced pressure in the rock mass at a distance from a blasthole. The methodology of monitoring and a few examples of actual field monitoring are detailed in this paper. The responses of the rock in the near-field of a blasthole under dynamic loading have been documented to predict fragmentation and throw. The proposed method has also been used in limited cases earlier by the author to predict flyrock using a semi-empirical method and trajectory equation. The pros and cons of the method are discussed while throwing light on the actual response and the prediction of fragmentation and throw of blasted rock.CITATION:Raina, A K and Murthy, V M S R, 2015. Measurement of blast-induced pressure in bench blasting and deciphering explosive performance through rock mass response analysis – a methodology, in Proceedings 11th International Symposium on Rock Fragmentation by Blasting, pp 501–508 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 24, 2015

Devitrification of a glassy volcanic ash equivalent to an alkaline trachyte in composition has resulted in the formation of an interstratified illite-montmorillonite with an 1:1\1 content of 1:4 as the principal clay mineral.A high concentration of potassium ions and a deficiency of magnesium ions favoured the formation of the potassium-bentonite.A poorly ordered mica mineral, equivalent to illite, was produced by weathering of potassic feldspar. Subsequent degradation of the illite through the loss of potassium was responsible for the formation of several interstratified minerals with very approximate 1:1\1 contents of 4: I as minor components.Other authigenic minerals present in small amounts were u-cristobalite, sepiolite, and the zeolite clinopitolite.The non-swelling character of the potassium-bentonite makes it economically unattractive...

Jan 1, 1967

By M Passmore, N Poznik

Olympic Dam is a world-class deposit and is unquestionably one of the most geologically, structurally and texturally complex orebodies in the world. As development advances into the Southern Mine Area (SMA) the geological understanding is rapidly evolving as underground drill rigs are prioritised to provide the additional data necessary to convert Indicated and Inferred Resources into Measured Resources. The SMA represents approximately 70 per cent of Olympic Dam’s total resource and is significantly more complex when compared to the Northern Mine Area with respect to the diverse nature and origin of lithotypes, rock mass characteristics and the extent of major structures controlling primary mineralisation trends.Recent mine development into the central SMA has been impacted by a major structural gouge zone. Sound geological interpretation allowed mine geologists to successfully integrate their local understanding of the distribution of lithotypes with critical geotechnical data, chiefly rock quality designation (RQD), to delineate and better predict this major structural gouge zone. As a direct result, development rates improved whilst also increasing awareness for the importance of sound geological interpretation utilising all available data. In order to maximise predictability across all systems in place through the mining geology value chain, the integration of geological and geotechnical data in a geotechnical RQD block model provides an additional tool to assist in preventative solutions for complex problems to achieve a proactive mining environment.This paper details the methods used to build the RQD block model, the geostatistical estimation parameters, 3D geotechnical domain wireframes, challenges regarding legacy approaches, and collection of geotechnical information and incorporating/linking geotechnical data with geological features, including the use of grade and lithotype domains. Although the geotechnical block model proved difficult and complex to construct, the resultant product has seen successful integration of geological and geotechnical data into mine planning providing higher resolution of critical parameters for local mining areas.CITATION:Clark, J M, Passmore, M and Poznik, N, 2017. Olympic Dam rock quality designation model – an integrated approach, in Proceedings Tenth International Mining Geology Conference 2017, pp 27–36 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 20, 2017

By B Belle

"Mines around the world are inherently and operationally diverse. Current methodologies for the design of mine ventilation and cooling infrastructure involve controlling major safety and health hazards. Globally, it can be estimated that mine ventilation systems from various commoditiescirculate over 150 000 m3/s of exhaust air through shafts. Additionally, over 2 000 000 workersare transported every day through shafts in labour-intensive mining countries like China, India,Southern Africa, and the Americas. A key objective of this paper is to share experiences and provide a case for the revision of ætime-honouredÆ ventilation design parameters based on a benchmarking exercise on design exhaust shaft velocity from various global operations (gold, diamond, platinum, coal and base metals). An active fi eld observation on exhaust shaft velocity has indicated that, regardless of the commodity or continent where the mine operates, almost all life-of-mine (LOM) design parameters provided are in the same range of 20 m/s to 22 m/s, which is not convincing considering signifi cant variations exist in shaft depths, geography, commodity, operating and capital costs. From a due diligence perspective, there are no documented views that are available on the most widely used design exhaust air velocity. Based on the global exhaust shaft velocity data, it is noted that a significant portion of shaft velocities are outside the current design velocity of 20 m/s (some operating up to 30 m/s) and other signifi cant portions of the exhaust shafts operate in the critical velocity range. In the case of Australian coal mines, limited data suggests that none of the mines have ever reached the LOM design exhaust shaft velocity. It is self-evident that when the shafts are not operating at their design quantities either the mine system resistance is low or the ventilation and main fan is operating ineffi ciently. The most common reasons given for not reviewing the shaft system were, ætime-honouredÆ design parameter are being used and cannot be changed, mine fan pressure limits, possible fan blade damage, possible spontaneous combustion risks, leakage or simply did not consider such a possibility. In conclusion, the study has reiterated the historic lessons that a safe and expensive airway should not be utilised uneconomically by circulating too litt le air through it."

Jun 1, 2012

By J Cronin

For the last decade, we have read about the great technical innovation that is coming to the mining industry that will increase safety and productivity. There is consensus that it will be a technical innovation that will produce a step change in mining costs and outputs (as opposed to bigger machines or less people); however, this innovation (while freely available) has not taken hold in the industry. While there are a few mines that have embraced technology, the majority of underground mines simply do not have the expertise or technical capability to implement innovation and automation.With unexploited mineral deposits becoming deeper and more remote, and thus more hazardous to mine, telepresence offers the ability to remotely execute production tasks while separating personnel from hazards. As the technologies required to deliver telepresence mature, the potential for there to be no personnel underground during production activities is becoming a reality (the ‘dark factory’). So significant is the capacity of telepresence to mitigate risk, it is proposed that it be included as a separate entry in the hierarchy of hazard mitigation controls.Technical innovation such as the optimised short-term interval control of the production process and the automation of underground mobile fleets offer significant increases in production along with lower operating costs. This paper explores the most critical components for the successful implementation of technology in underground mining; redundant, robust and high-bandwidth communications networks to carry data from distributed networks of smart sensors and to convey teleoperation commands; and high-definition video to provide operators with detailed, real-time data. The days of analogue ‘leaky feeder’ as a base case for communications are over. The human resources required to support the expected wave of innovation are significant and will be difficult to maintain in remote areas as the same skills and expertise are in demand in other industries.The paper highlights barriers to innovation in the mining industry, and a lack of technical and scientific expertise within the industry to be able to identify, implement and manage technologies that can increase safety and productivity. As well, an over-reliance on basic net present value (NPV) financial analysis that is used in the industry punishes investment in technology (capital expenditure; CAPEX) and accepts higher operating expenditure (OPEX) due to the discounting of future savings in operating costs.CITATION:Cronin, J, 2017. Telepresence – the application of remote control and automation technologies for increased safety and productivity, in Proceedings 13th AusIMM Underground Operators’ Conference 2017, pp 213–224 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 16, 2017

This paper describes certain analytical methods used at the Rosepery Mine and Treatment Plant of the Electrolytic Zinc Co. of Australasia Ltd., which are not generally in use and may therefore be of more interest than a description of the normal routine methods which are used in most of the mining assay laboratories of the Commonwealth, and which have been published previously.The ore mined and treated at Rosebery is of a complex nature and demands closer control in the concentrating plant than is necessary on some other similar mining fields.It is necessary for the mill shift supervisors to keep constant control on the grade of lead and zinc concentrates produced on their respective shifts, and further, it is essential to maintain an economic compromise between grade of concentrates and the recovery of the particular concent:t:ate. This necessitates a more frequent check on concentrate grade tp.an is provided by the daily assays carried, out by the assay office. Rather than employ trained ,assayers on shift work, "quick methods" of analysis, which could be carried out by the operators, 'were adopted.'In such methods, it is desirable that the necessary manipulation should be reduced to the following:-a. Taking the sample, drying and mixing.b. Weighing the necessary amount of sample-for assay.c. Adding the reagents for use in the assay without change of beakers.d. Titration and calculation.Such a contraction of, the normal technique would be impracticable for many determinations, but in the case of lead...

Jan 1, 1949

By Dhar B. B, Gupta R. C

Grinding of iron ore is an essential step to utilise ore fines for pelletisation needed for DRI units. While preparing iron ore pellets for DRI production, the iron ore needs extensive grinding which is highly energy consuming step causing the process to become non-viable in some cases. In the present paper an attempt has been made to evaluate grinding performance of thermally treated ore compared to normal ore grinding. Such thermal pre-treatment has been found to reduce the energy requirement with lower consumption rate of grinding media. It has been observed that by applying thermal shock the ore is rendered weak with improved grindability. The stresses generated due to thermal treatment may extend existing micro-cracks in the ore and in some cases it may even nucleate fresh cracks. Experimental studies carried out on thermally treated hematitite ore reveals that the heating to 400¦C followed by water quenching can cause a reduction of 45 per cent in grinding energy. The paper gives the details of the experiment and the Results.

Jan 1, 1999

The Autogenous Fine Grinding Kelsey Axial Displacement (KAD) Mill The marginal improvements which continue to be made to fine grinding practices have exposed the limits of conventional technologies and highlighted the need for a radically new approach. The patented autogenous Kelsey Axial Displacement (KAD) Mill design consists of a rotating spherical grinding chamber, which shares the same spherical centre as the shaft-mounted counter-rotating disc assembly. The axis of the disc assembly can be inclined to the axis of the spherical grinding chamber by pivoting the disc shaft about the common spherical centre. The inter-particle energy transfer required for breakage results from particle velocity differentials created by the discs intercepting the rotating mass. Particle size reduction is concentrated in high shear zones, which envelop the outer surface and periphery of the discs. This paper traces the development of the KAD Mill from pilot to commercial scale. Pilot work covers a range of minerals including magnetite, calcite, dolomite, barite, limestone and talc. Test results include open and closed circuit operation in wet and dry modes. Conventional milling constraints and energy consumption issues are addressed while new dimensions are added to the feed size range acceptable for wet and dry grinding to fine and ultra-fine sizes.

Sep 13, 2010

Recovery of Fine Gold Particles from Philippine Gold Deposits by Enhanced Gravity Concentration and Flotation The objective of the study is to determine the applicability of enhanced gravity concentration (EGC) and flotation for gold recovery. While gravity concentration methods have long been applied to gold ores, especially to free-milling types that requires minimal beneficiation, flotation for gold recovery has not yet taken hold as a major operation in the Philippine setting. In this study, the application of EGC and flotation for gold is applied and compared to the existing methods for gold recovery. Two samples, with assays of 7.315 and 5.333 g Au/MT (samples 1 and 2, respectively) are used for this study. These samples are subjected to mineralogical studies and is found to have a gold-particle size ranging 10 to 200 microns. To verify the separation size, the mesh-of-grind (MOG) is used as the primary parameter for experimentation. Initially, the samples are stage-crushed, ground, and subjected to EGC using a Falcon SB40 Concentrator. Based on the results, the two samples showed that recovery increases with a finer MOG. The ratio of concentration (K) decreases with a finer MOG. This shows that there should be sufficient liberation of the gold values for EGC to be effective. The effect of the enhancement is to pronounce the difference in specific gravity of the minerals, promoting better separation. This is validated by the high recovery values of 86.97 per cent and 98.73 per cent exhibited respectively for samples 1 and 2 (at 54 microns). For the flotation runs, sample 2 with an average particle size of 80 per cent passing 74 microns is examined using thiocarbamate-based collectors for roughing and subsequently exhibited a recovery of 96.32 per cent. At this point, the concentration ratio (K) is noted as an important efficiency indicator for flotation process since it yielded a very low-mass and high-metal content concentrate.

Sep 13, 2010

The phosphorus content of the banded iron formation (BIF) and of the associated iron ore deposits in the north west of Western Australia is known to vary widely, a fact which has considerable econ~mic significance. Trendall and Blockley (1970) have described the variety of textural appearances of apatite in the Hamersley Group BlF, and suggest that apatite may account for the entire phosphorus content of the unaltered BIF.A preliminary investigation using an M.A.C. electron microprobe analyser has shown that, at least in some iron ores and in partially enriched BIF and associated shales, the phosphorus occurrence is more complicated than this. A suite of samples was examined from one location which covered the entire Dales Gorge Member and some adjoining macrobands in the Mt. McRae shale, together with samples selected for their high phosphorus content, degree of ore enrichment, and position relative to the enrichment zone. Calcium apatite was not observed in any sample of ore from this sequence, despite its ubiquitous occurrence in the BIF. Silicate mineralogy in the enriched regions also differs from that in the BIF, but this change has not yet been studied in detail.The phosphorus content of goethite in one orebody is often high and appears to be in solid solution in the goethite structure. It shows little or no variability on a micro-scale within a grain, except where theremay be a zoned enrichment near boundaries and solution channels. There is also a limited solubility of phosphorus in hematite (the maximum observed by the author is 0·1 per cent P); but where the hematite is martitic (after magnetite) its phosphorus content is always low or zero. In some bands, martitic hematite has been hydrated to goethite, and this also has a very low phosphorus content. Phosphorus was not found in the silica or silicates in the ore, and even when iron enrichment is just beginning, a limited suite of samples from the BIF suggests that the phosphorus content of the chert microbands is almost entirely in the microscopic goethite nuclei (after riebeckite) scattered throughout the chert. The ability of goethite and hematite to accept phosphorus...

Jan 1, 1973

Experimental results are presented for the anode overvoltage as a function of current density for different alumina concentrations in an alumina reduction cell. Voltage changes due to the electrolyte resistance and also the decomposition voltage, have been evaluated as a function of alumina concentration and anode current density. From these values of voltage, changes in the total cell voltage have been derived for changes in alumina concentration for different anode current densities. The results show that for each operating current density there exists a discrete alumina concentration that defines a minimum reduction cell voltage. Discussion is made about potential savings in power consumption when the alumina concentration is controlled.INTRODUCTIONThe standard procedure in the aluminium industry when analysing the cell-voltage required for the Hall-Heroult process for reduction of alumina, is to subdivide the total voltage into the following components (e.g. Pearson, 1955; Maritell, 1960).1. ohmic drop through busbars and joints2. ohmic drop through cathode lining3. ohmic drop through anode4. ohmic drop through electrolyte5. overvoltage at anode6. electrolytic decomposition voltage.(Overvoltages ,at the cathode are of negligible magnitude at all practical current densities.)It is understandable that the voltages assigned for each factor invariably differ for different workers...

Jan 1, 1965

By H W. Wu, T Harvey

An overview is given of two new developments in mine atmospheric monitoring. A new personal dust monitor (PDM) that gives real-time respirable dust readings is discussed. The unit is mounted within the minerÆs cap lamp battery and internally measures the true particle mass of dust collected on its filter. Samples are available for later mineralogical analysis and results do not exhibit the same sensitivity to water spray as optically-based measurement approaches. The technique achieves microgram-level mass resolution even in the hostile mine environment and reports dust loading data on a continuous basis. The monitor has been evaluated under an Australian Coal Association Research Program (ACARP) grant and is being adopted for statutory mine respirable dust determinations in the United States (US). The monitor has particular application for determining location of high dust sources. It can evaluate the efficiency of engineering means of suppression and other approaches to reducing dust levels. It has been recognised that the PDMÆs unique measurement approach has application to allow real-time atmospheric diesel particulate matter (DPM) monitoring. The industry has no real-time atmospheric DPM monitor at present. Recent surveys in New South Wales and Queensland show significant numbers of miners continue to face full shift DPM exposures in excess of internationally accepted levels. Real-time DPM monitoring will allow the industry to pinpoint high exposure zones where a number of trucks and other vehicles work in areas of poor ventilation. Knowledge of high DPM concentration zones allows efficient modification of work practices to reduce underground minersÆ exposure. Approaches to uses of the DPM form of the monitor and the design of tag boards are discussed. Some outcomes from mine tests with both these new instruments are given.

Jan 1, 2008

The Greymouth Coal Project is a proposal to mine by the application of proven hydraulic, and room and pillar underground mining methods; and to process the equivalent of an average of 1.7 million tonnes per year over a forty-year period. The proposed mine site is located ten kilometres north of Greymouth, on the west coast of the South Island of New Zealand. Of the three separate mineable seam groups, the thick Main Seam Group, which makes up 77% of the total resource, will be mined by hydraulic mining technology.   It is proposed to market and produce a high volatile bituminous type coal with low ash (6%) and sulphur (0.4%). Because the inherent ash content is low, the requirement for coal treatment will only be the use of a single cell jig circuit to control the effects of rock dilution and partings. The resulting coal product is tentatively planned to be transported by rail to the port at Lyttelton for loading on to Panamax or Post Panamax size vessels.

Jan 1, 1997

Hatches Creek has been inactive since 1961, but with better metal prices, interest in the field is reviving.The mixed gravity concentrates which were unsalable in 1951 have been experimentally separated into salable wolfram, scheelite, and bismuth-gold concentrates, and a flow sheet incorporating magneticseparation and flotation has been developed.

Jan 1, 1965

Stratiform lead-zinc mineralization at the Pegmont prospect occurs as a 4-6 m thick body interbedded within arkose, schist, amphibolite, and pegmatite of the Kuridala Formation in the Eastern Belt of the Lower Proterozoic of northwest Queensland.The overall structure of the body is that of a strongly crumpled east-dipping sheet. In detail it is subjected to complex and irregular deformation.Gossaneous outcrops of the mineralised body are anomalous in Pb-Zn-Ag content and have been traced, discontinuously, over about 36 km2 in a NNE-trending belt.Below the zone of oxidation, which reaches 25-40 m below the surface, the primary sulphides are galena, sphalerite, and pyrite.Drilling on a 2 km2 area near the discovery outcrops indicates fairly uniform grades of lead and zinc.Changes in thickness of the mineralised body are gradual.

Jan 1, 1977