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By M BSckstr÷m

Acid rock drainage (ARD), commonly found in vicinities of sulfidic mines, possess properties capable of widely affecting the surrounding environment by acidification and heavy metal pollution. In most ARD treatments, various alkaline sources are used to neutralise the acid produced. Utilisation of highly alkaline fly ashes instead of raw materials is a cost-effective alternative, which lately have become increasingly popular. In laboratory batch experiments, neutralising capacity of fly ash was studied during 20 days. ARD was added to the fly ash once a day, for each increment the liquid to solid ratio (L/S ratio) was increased. At an early stage of the experiment (day 6, L/S ratio 12), the concentration of barium in solution unexpectedly increased by a factor of 50 (from 200 to 10 000 ¦g+l-1). This high concentration also sustained the following two days (L/S ratios 14 and 16) before dropping to the original level. pH showed a slight increase during these observations (pH 12.4 - 12.7). The phenomenon was also observed in a parallel and identical series. In addition to barium, aluminium and strontium clearly increased in the same manner, however not as much as barium. Furthermore, concentrations of chromium and molybdenum noticeably decreased at these distinct L/S ratios (12, 14 and 16). The behaviour of barium and subsequently strontium, aluminium, chromium and molybdenum is only partially understood. The decrease of chromium and molybdenum is suggested to be due to incorporation into the interlayer regions of hydrocalumite (Ca4Al2(OH)12(OH)2+6H2O), replacing the hydroxide groups, which also explains the increase in pH. Moreover, the increase of barium, strontium and aluminium could be attributable to dissolution of the silicate mineral celsian (Ba,Sr(Al2Si2O8)). Alternatively, barium and strontium increase could be explained by dissolution of a Ba,Sr(SO4)-solid solution and aluminium increase by dissolution of hydrocalumite or ettringite.

Jan 1, 2008

By A D. Strand

The Coeur dÆAlene mining district in northern Idaho, USA is the second largest producer of silver in the world. The Proterozoic Revett Formation hosts most of the mesothermal Ag-Pb-Zn vein ore in the district; it consists of informally designated lower, middle, and upper members. All three members show up to an order of magnitude of southward thickening across the regionally significant Osburn fault. Changes in thickness of the Revett Formation across the Osburn fault reflect a major, down-to-the-south, crustal-scale fault that:was active during sedimentation, was periodically reactivated during the structural and metallogenic history of the district, and likely provided first-order control over regional fluid flow during mineralization events. Where vein structures intersect favourable strata, they produce rich ore; where vein structures cross unfavourable strata, they are poorly mineralised or barren. The most favourable host rock in the district is quartzite, which accounts for the large production from the quartzite-rich Revett Formation.The district has five main types of hydrothermal alteration:feldspar destruction, hydrothermal bleaching, carbonatisation, sulfidation, and silicification. Feldspar destruction is the most extensive and pervasive type of alteration, involving the district-wide absence of feldspar from Belt Supergroup rocks. Hydrothermal bleaching results from the destruction of hematite; it forms alteration envelopes that extend for tens to hundreds of metres into the wall rocks around many of the mineralised veins. Siderite alteration is most diagnostic of mineralisation, forming alteration envelopes that extend for tens to hundreds of metres into the wall rocks around all mineralised veins. Fine-grained arsenopyrite and/or fine-grained pyrite commonly form alteration zones adjacent to high-grade ore shoots that extend for metres to tens of metres into the wall rocks. Widespread silicification is most easily recognised by the presence of numerous quartz veins.

Jan 1, 2002

In todayÆs evolving and globalised world, mining companies are being pressured to move beyond compliance towards long-term sustainability and sustainable development. Companies are expected to æengageÆ communities and measure the success of these engagements without a clear understanding of æhowÆ to do this. This move, away from compliance, develops more of a focus on sustainability and æcommunityÆ social responsibility rather than corporate social responsibility. This shift leads to the development of world-class projects that provide sustainable development for people, reduce the incidence of costly delays, and promote good global citizenship for companies. The process of æengagingÆ communities in mining project design and development leads to sustainable development, a stronger license to operate, and a reduction in social and political risk. To create this mutually beneficial relationship between communities and companies, communities must be æengagedÆ in the project development and risk assessment processes as early as possible, preferably during the exploration or the concept phases. How to create this æengagementÆ and manage this risk will be discussed.

Jan 1, 2007

By Guo-Zheng J

This paper describes the risk management strategies adopted to control unstable slopes in the east open pit of the Daye iron ore mine. Extensive experience has been developed over the last 35 years in the management of pit wall instability resulting in the successful excavation and reinforcement of pit slopes over 350 m in height.

Jan 1, 1994

By Hawkins L. V, Seedsman K

A combined reflection seismic and magnetic survey off the south coast of New South Wales has revealed six distinct reflection horizons within the Lower Triassic- Upper Permian sequence, and has enabled the upper part of the Illawarra Coal Measures to be mapped in considerable detail. Large magnetic anomalies in the eastern half of the survey area appear to originate in the Gerringong Volcanic Sequence which forms the magnetic basement in this survey. Small residual anomalies in the western half of the area can be correlated with small scale faulting and folding in the uppert part of the Illawarra Coal Measures, as revealed by the seismic reflection survey. A synclinal axis striking at approximately 55¦ has been mapped near the western margin of the survey area, and areas of faulting and folding have been outlined by com- bined analysis of seismic and magnetic results.

Jan 1, 1969

By Hunter GW

This paper gives an account of the filling system at Mount Isa from surface fill production to stope discharge underground. A brief explanation of the surface facility and reticulation is given prior to the discussion on aspects of underground reticulation. These include fill hole types, pipe and breastplate installation, wear characteristics, etc. The different types of fill and their respective applications is mentioned as a prelude to a general overview of the mining considerations associated with fill placement and its role in the long term planning strategy at Isa Mine. Some practical aspects of stope preparation and filling procedures are outlined for the various stoping methods. Finally a brief outline of future fill developments is given.

Jan 1, 1982

By Menne D. M, Ladyman R

Camel Creek Mine operated by Lynch Mining Pty Ltd is located 65 km west of inghain and 160 kin north west of Townsville in North Queensland. (Figure 1). The Camel Creek gold mineralisation was discovered in mid-1987 in an area previously known for its tin workings. Mining commenced in January 1989 after an oxide reserve of 1.2 million tonnes @ 2.1 g/t gold had been delineated. The first gold pour was in May 1989. The mine developed into a medium sized open cut operation, with full site facilities. The initial mining rate was 500 000 tpa utilising run-of-mine (ROM) heap leaching to recover the gold. By the end of 1990 the wider orehodies were mined and efforts were focused on the narrow orebodies, of width typically less than three metres. Smaller earth moving equipment was employed to selectively mine the narrow orehodies leading to a decrease in the mining rate to 200 000 tpa. The Red Gold deposit (80 000 tonnes « 3.0 g/t to 18 in vertical) was mined in mid-1990 and ore was hauled approximately 8 kin to the Camel Creek heap leach operation. The ore was hauled in a dedicated campaign after being stockpiled. The cost of dedicated ore haulage ensured that only the more exceptional of the remote orebodies could be mined in this manner. The Golden Cup orebody, some 20 km from Camel Creek, was too distant to permit ore haulage. However, this prospect contained sufficient gold (initially 90 000 tonnes @ 3.0 g/t) to warrant the installation of a small mobile adsorption facility. Construction of the second heap leach operation commenced in late-1990. Gold production commenced in early April 1991. Mining of several smaller orebodies remote to the second heap leach facility has been undertaken and further mining is planned. This paper outlines heap leaching practice at Camel Creek Mine and summarises the success of the Golden Cup heap leach.

Jan 1, 1994

The Black Star lead and zinc ore-bodies, situated in the western zone of mineralisation at Mount Isa occupy an area 2000 ft. long with varying widths from 100 ft. to 300 ft. The strike is N5°W, and the average dip 60° West.To test at depth the potentialities of this area, an extensive diamond drilling campaign was commenced on 16th October 1927. It was continued, with from one to six machines working, until the end of 1931. During this period, 26 inclined holes, with an average depth of 1224 ft, and a total footage of 31,828 ft. were completed. A vertical hole, 2452 ft. deep, for comparative purposes, has been omitted.These drilling operations came directly under the charge of G J Gray, General Superintendent of Mount Isa Mines, and, in the early stages were supervised by E. D. McDermott, of the Mining Trust, London. The foremen, who were in charge of various sections of the drilling operations, were: H Vale, F Bray, J Winston and A A Sanstedt.

Jan 1, 1932

By Weller K. R, Stewart P. S B, Restarick C. J

The performance of the Renison tin concentrator was assessed in detail for two arrangements of the three available ball mills. With two mills used for primary grinding and the third for regrinding table tailing, the concentrator recovered 65.3 per cent of tin in the three tin concentrates produced by tabling, vanning and flotation at a calculated overall grade of 37.5 per cent tin prior to batch dressing. In the second arrangement one mill was used for primary grinding and two mills for separate regrinding of table tailing and sulphide concentrate. The metallurgical effective- ness of the change was somewhat obscured by unintended changes,i.e. an increase in the assay of the fresh feed from 1.38 per cent to 1.1+6 per cent tin and unresolved changes in the sulphide rougher flotation and tabling. However, using the results from a detailed size by size analysis of the behaviour of ore components in appropriate parts of the plant, it proved possible to show that, had the two unintended changes not occurred, up to 5 per cent

Jan 1, 1977

By A E. Annels, M D. Raine, I M. Platten

Lode-gold systems are often characterised by a high to extreme nugget effect (>50 per cent), and the presence of coarse gold particles (>100 ¦m in size). They rank amongst the most difficult of ore deposits types, in terms of producing an accurate and precise resource estimate. Their effective sampling is generally difficult because of the relatively low concentrations involved and erratic nature of the gold particles. Grade continuity is usually less consistent than gross geological continuity, and is typified by the localisation of grades within discrete oreshoots. In most cases drilling, particularly diamond drilling is an effective measure of global geological continuity, whereas grade can only be reliably resolved from underground development. Depending upon drill density and geology, it is unlikely that anything above an Inferred Mineral Resource can be estimated from surface drilling alone. Underground development, in-fill drilling and, potentially, bulk sampling or trial mining will be required to delineate Indicated and Measured Mineral Resources and subsequent Ore Reserves. Grade estimation will have to account for highly skewed and often multi-modal populations, extreme values, a high nugget effect and low geostatistical ranges. A clear geological model that honours both geological and grade continuity must drive the resource estimation process.

Jan 1, 2003

By Ofori-Ansah K

The zeta potential on the surface of activated orit carbon were estimated in lhe presence of selected cations and anions that are normally associated with gold bearing ores in Kalgoorlie area of Western Australia. Additions of such ions to solution of varying pH shifted the isoelectric point of carbon from pH 4.45 to pH 7-8.3, while the anions moved Lhc isoelectric point 10 less than pH 3.2. In the presence of gold cyanide SoluLion additions of spectator ions indicated the isoelecLric poilll to be aL pH less than 3.2; the only exception was for Fe" ion where the isoelecLric point was at pH 5.9. The decrease in zeta potential appeared to be related to the counter-ions present. The decrease may also be related to the adsorption of hydroxyl ion complexes that are likely to be formed when cations are present in the solutions.Gold adsorpLion by activated orit carbon from gold cyanide solution seem to be indicated by the magnitude of zeta potential on the carbon surface. An attempt is made to relate gold adsorption and zeta potential on carbon surface with the pH of the medium.

Jan 1, 1984

By S Long, D Carnovale, L Louwrens

The Mt Wright underground mine (MTW) is located near the town of Ravenswood in north Queensland and is operated by Carpentaria Gold – a wholly owned subsidiary of Resolute Mining Limited.The Mt Wright mine has gone through many stages, from the conception and implementation of the world first ‘sub-level shrinkage’ stoping (SLS) with continuous fill mining method in 2010, through to steady state production. These have been outlined in detail in papers presented by Mackay (2011) and Mackay, Long and Koen (2014) at previous Underground Operators Conferences.Since the last paper was presented, MTW has experienced significant change in two key areas.The first significant change was the discovery of a previously unknown hazard in the form of flat rilling events (FREs) from closed drawpoints (DPs). These events are believed to be unique to MTW and pose a significant risk to both the safety of personnel and the business as a whole. The paper will discuss this hazard and the evolution of the controls and practices that have been introduced to mitigate the risk posed by the identified hazards. The material involved in these events is extremely dry, fine and hot.The second significant change is an altered stress regime bought on in part by a change in the production front orientation and a general deterioration in ground conditions in some areas of the mine. This has caused some production interruptions at MTW. The second half of the paper will describe the challenges encountered, the mechanisms behind these challenges and the strategies implemented to safely return MTW production to planned levels.It is believed that other operations can learn from the issues mentioned above, and the paper has been written with this in mind.`CITATION:Long, S, Carnovale, D and Louwrens, L, 2017. Mt Wright – managing unique risks, in Proceedings 13th AusIMM Underground Operators’ Conference 2017, pp 295–304 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 16, 2017

By Morley C

The Mount Charlotte gold mine is located 0.75 km east of the General Post Office in Hannan Street, Kalgoorlie WA and about 3.5 km north of the Fimiston Operations on the famous Golden Mile.Mechanised underground bulk-mining at Mount Charlotte has been in continuous operation since 1963. For the 30-year period ending December 1992, the mine produced 22 million tonnes (Mt) of ore for a recovery of 2.73 million ounces. During 1991/92, the mine produced 1.53 Mt of ore at a head grade of 3.15 gramshonne (g/t) for a recovery of 135 822 ounces.The principal ore source at Mount Charlotte has been the Charlotte Orebody which is now largely mined out. Since 1990, approximately 75 per cent of production has been sourced from the Reward Orebodies. The Charlotte Orebody was a relatively homogeneous quartz stockwork with simple geometry and average bulked grades in the range of 4.0 to 5.5 g/t. This is in contrast to the Reward Orebodies and the more recently defined Charlotte Deeps and Maritana Stockworks, which have complex grade distribution and geometry with lower average bulked grades (2 to 4 g/t). The lower grades are principally due to the decreased density and volume of stockwork venation and related vein halo alteration. Typically, these stockworks comprise a patchy mosaic of quartz veins and vein swarms, with irregular distribution and geometry within the quartz gabbro host rock.

Jan 1, 1993

By Prakash AJ, Singh PK, Dhar BB

Safety and stability of underground mine openings, coal pillars and water dams in the near vicinity of operating surface mines are endangered from excessive blast induced vibrations. This paper deals with the investigations carried out in four coal mines. Simultaneous measurements at equal distances from the source indicated higher level of vibration on the surface than those produced in the underground workings. The values of peak particle velocity (PPV) measured on coal pillars, body of water dam were lower than those measured on roof and junctions of the roadways. The parting of coal (3-4.5 m) between two sections vibrated with higher PPV compared to the roof of top section and floor of bottom section. In one case the influence of total charge fired in a round was significant in generation of vibration compared to the maximum charge/delay where monitoring was done vertically below the source.

Jan 1, 1995

THE following paragraphs represent an endeavour to describe, briefly the equipment used for the manufacture of sulphuric acid and superphosphates by the Corporation.SULPHURIC ACID PLANTS.Two separate units are in operation, No. I Plant working on sulphur dioxide generated from pyritic ore, No. 2 Plant working on sulphurous gases obtained from the Huntingdon-Heberlein desulphurizing process. The latter plant is unique in being the first installation for the successful use of these gases.

Jan 1, 1918

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

By H R. Phillips

Fresh air intake in an underground coal mine is of critical importance to the occupational health and safety of workers due to the dynamic, confined and dangerous nature of the mining environment. In most coal mines in South Africa, belt road is not separated from the fresh air intake to the sections. Intake air to coal production faces generally contains dust generated by conveyor belts, transfer points and travelling roads. Long roadways (up to a few kilometres in some of the existing mines) to the coal sections are involved in the ventilation circuits of individual sections. This leads to a progressive increase in the dust levels in the intake fresh air and thus high dust levels in the air delivered to the working sections downstream. In the process of reducing worker exposure to dust in the face area, attention to the monitoring of fresh intake air is generally given a low priority. This paper summarises the intake dust levels measured in selected South African underground coal mining sections over the past five years and its use as a parameter in assessing worker exposure to dust through a newly developed model called the Dust Exposure Level Index (DELI). Based on the measured data of the South African coal mines, the average section intake dust level was 0.78 mg/m3. Approximately 60 per cent of the samples collected for the study have exceeded the 0.5 mg/m3. The intake dust level measured at a longwall face was much higher than in the CM headings. The measured section intake dust levels furnish the South African coal mining industry with the latest depiction of the level of face area dust contamination due to the intake air. Further, this paper demonstrates the use of intake dust level as a parameter in estimating exposure levels of workers, as it clearly plays as a corner stone in effective control of exposure to face area respirable dust. It must be borne in mind that intake dust is a base level to the mine worker exposed to dust without carrying out any additional work in the section. If the intake air is seriously contaminated by airborne respirable dust; then the exposure of the workforce in the section will constantly be elevated by that background dust level.

Jan 1, 2005

This paper will address this question from the point of view of a drill and blast engineer or researcher working in open cut and underground mining operations. The paper will establish a common set of reference standards for high-speed imaging and data capture, which engineers and researchers can apply when deciding which type of imaging technology is appropriate. It will present an overview of current image analysis technologies and practices in use across a range of appropriate scientific fields and draw lines of commonality of approach between these fields and the field of mining and blasting applications analysis and research. In addition, the paper will examine the different technologies from an image quality and data stream reference point, ease of operation, cost, and reliability parameters. Finally, this paper will present an argument for the hybridisation of established and new technologies which could provide a more beneficial approach to the use of imaging as a tool of quality control, research and analysis in the mining based industries. This will include a novel approach to digital high-speed imaging and data analysis in the field, which should deliver high-quality images and data analysis in a time frame that is more appropriate to the need for immediate action, analysis and problem solving.

Jan 1, 2007

Mineral sands are different to almost any other commodity; however, it shares similarities with other commodity types, such as the importance of quality constraints of iron ore and coal or the importance of physical properties of diamonds. The mineral sands industry consists of two principal product streams; titanium dioxide minerals û in the form of rutile, ilmenite and leucoxene, and zircon. The principal valuable heavy minerals (VHM) include ilmenite, leucoxene, rutile and zircon. Variations of other titanium minerals occur between the end members of ilmenite and rutile, including pseudo rutile and anatase. Most mineral sands deposits are found in unconsolidated fossil shorelines several hundreds of metres to tens of kilometres and occasionally hundreds of kilometres inland from the present coastline. Mineral sands orebodies essentially fall into two categories based on the mode of deposition: alluvial or aeolian. Alluvial deposits are further split into marine beach placers (or strandlines) and lacustrine heavy mineral (HM) accumulations. Exploration for mineral sands involves the positive identification of key criteria leading to the focus of exploratory surface sampling, augering and drilling. Assaying is primarily focused around determining the percentage of HM contained within a given sample. Other results of interest include clay fines, sand and oversize. Metallurgical/mineralogical assessment is often undertaken via laboratory scale bench tests that replicate the wet concentration and dry mill processing routes. The most critical component in resource assessment for mineral sands is about quantifying HM grade, then mineralogical assemblage and then quality of those mineral species. This will determine whether a mineral sand final product is marketable or not. Mining of mineral sands is conducted either wet or dry. Wet methods are generally preferred for large tonnage, unconsolidated and low clay orebodies. Where ground conditions are hard and orebodies are small, high grade and discontinuous, dry mining techniques are generally employed. Concentration of mineral sands from the primary ore is carried out in two sections; wet, utilising sizing and gravity differentiation between HM, VHM, clay and quartz, and dry, exploiting the magnetic, electrostatic and to a lesser extent specific gravity (SG) properties of the minerals of interest. Mineral sands exploration, mining and processing faces the same operating challenges as the rest of the resource sector. Added to this are the issues that are unique to mineral sands and to which the industry devotes considerable resources to developing solutions.

Jan 1, 2009

By G S. C Murray

Major mining projects are developed with the assistance of lending institutions who provide hundreds of millions of dollars in funding over several years, and of course expect those funds to be returned with interest. Two Australian banks have adopted the Equator Principles, an emerging financial industry benchmark for assessing and managing environmental and social risk in project financing. Project financiers have encountered environmental and social issues that are both complex and challenging, particularly with respect to projects in the emerging markets of Asia-Pacific and elsewhere. There are many recent and historical examples of failures by resource companies to effectively manage their environmental, social, safety and security risks, some of which have caused the project to fail completely, and some of which have caused the temporary cessation of production. These events put the financial institutionsÆ funds at risk through inadequate management capacity and non-compliance adversely affecting the ability of the borrowers to repay the loans. They can also reflect adversely on the reputation of the lending institutions. In assessing these risks, lenders are increasingly looking at the track record of the borrower in its country of origin and in other countries where it operates. Lenders are wary of companies that have one standard for operations in a developed country, where the regulatory environment may tightly control what they do, and another standard for operations in countries where the regulatory regime is perhaps less stringent. Lenders may require environmental and social reviews or audits to be conducted on their behalf by competent third parties prior to a loan being approved, and annually over the life of the relationship. The mining industryÆs concept of the unwritten æsocial licence to operateÆ is highly relevant in relation to the delivery of community benefits that are sustainable post-mine closure. This paper provides examples of recent practices that support financial viability and sustainable development, as well as examples of some failures that have put lenders at risk.

Jan 1, 2007