Search Documents

By Cocker A, Kavetsky A

A numerical model describing blast fragmentation and damage in three dimensions has been developed at the Julius Kruuschnitt Mineral Research Centre (JKMRC) and applied to numerous blasting operations in mines throughout Australia. The model combines the rock structure (summarised by block size distribution) with blast strain energy and uses comminution theory to calculate the resultant block size distribution. The model distinguishes between rock breakage and failure, the former being defined as size reduction and the latter as block dissassembly. The background and basis of the model are discussed in detail and three case studies presented describing the application of the model to explosive performance evaluation, explosive selection and drill selection in Australian mining operations.

Jan 1, 1990

Recent work has shown that, in at least some instances of regional metamorphism, metamorphic diffusion has been restricted to such relatively minute distances (of the order of 1.0 mm and much less), that there is no clear, direct evidence of prograde metamorphic mineral reactions, and that metamorphic equilibrium does not appear to have been attained through even very small domains.A number of stratiform orebodies and their immediate metapelitic environments exhibit very large, seemingly "disequilibrium", assemblages of regional metamorphic index materials. One such, in north-eastern Australia, includes laumontite, prehnite, chamosite, stilpnomelane and related hydrous iron silicates, primary chlorite, sericite-muscovite, epidote, actinolite, biotite, almandine, andradite, metamorphic hornblende and clinopyroxene, scapolite, staurolite and sillimanite, all within a 20 metres length of a single diamond drill core. In this and several related occurrences it appears that metamorphism has involved very small scale in situ transformation of pre-existing materials rather than large-scale diffusion and reaction, and hence that the observed metamorphic minerals have probably been derived directly from precursor materials of sedimentary/diagenetic origin.It is concluded that the fluctuating seafloor interplay between warm, acid, concentrated hydrothermal waters with cold, alkaline, dilute seawater during stratiform ore formation, together with diagenetic processes, leads to the formation of a wide range of clay, chlorite, mixed-layer clay and clay/chlorite, and zeolite precursor materials and hence, later, to the complex assemblages of metamorphic minerals closely associated with some stratiform ores. Commonly included in highly localized assemblages of this kind are various minerals which, in conventional regional metamorphic studies, are generally regarded as indicating widely different grades of metamorphism.

Jan 1, 1982

The heavy media cyclones at Argyle Diamonds are subjected to extremely abrasive service conditions and have been the subject of a development program from the time the first ore was treated in the AKl processing plant. In the past ten years the cyclones have been re-engineered from a standard DSM design, in which some components would only last four days, to the current Argyle design in which the minimum component life is 175 days. Development has focused upon the elimination of turbulence in the cyclone and combating unavoidable abrasion through the use of appropriate wear materials.

Jan 1, 1996

Recent data contributions to New Zealand Mesozoic terrane geology confirm the consensus interpretation that New Zealand grew by the progressive addition of material by plutonic and accretionary processes along the Gondwana margin. The data also (1) emphasise the discontinuous but inter-related nature of these processes of continental growth, (2) better establish a direct Gondwana correlation of the Western Province and probable Gondwana provenance of at least some of the Eastern Province, (3) suggest specific times and places when passive or strike-slip rather than subduction regimes are recorded along the south Gondwana margin, and (4) potentially lead to interpretations emphasising parautochthonous rather than far- travelled relationships between many New Zealand terranes.

Jan 1, 1995

New Caledonia is a major metallogenic unit of the south-western Pacific Rim. Its mineral production is of world significance and it has an unusually well diversified mining history. New Caledonia's main metallogenetic potential is, however, associated with its unique ophiolitic complex and its important mineral- izations of nickel, chrome, cobalt and iron. Gold has been found in all the four basic tectonic elements of New Caledonia: the Central Massif, the West Coast basalts, the ophiolitic complex and the Caledonian North. Some analogies are attempted. Only the Caledonian North has supported mining operations (213 kg Au). More recently tenuous gold indications have been found within the ophiolitic complex, possibly associated with Oligocene plutonism.

Jan 1, 1987

By J H. Baker, P G. Beadle, J P. O&apos, Brien

In 1974 a preliminary study of the refractories industry in theRepublic of Indonesia was completed by Crown Lynn Consultants, a subsidiary of Cerarnco Ltd., on behalf of the Indonesian and New Zealand Governments. As a result of recommendations arising from that study the two Governments commissioned, in 1976, as a Bilateral Assistance project, an investigation into the potential of the refractories industry in Indonesia. Ceramco Ltd., was retained to carry out the study on behalf of the New Zealand Government. The Directorate-General of Chemical Industries, Directorate of Silicate Industries administered the project on behalf of the Indonesian Government. Indonesian counterparts to the New Zealand study team were provided by the Directorate of Silicate Industries.

Jan 1, 1978

The process selection and design aspects to treat primary ore in a new carbon-in-pulp (C.I.P.) plant while utilizing, where possible, existing equipment and infra- structure are discussed. The existing crushing plant, water supply, reagents, laboratory and infrastructure facilities from the heap leach have been upgraded and expanded to meet the C.I.P. plant requirements. The new power supply is from the North Queensland grid system. A series of metallurgical tests was carried out and a review of the data showed that the primary ore was amenable to conventional cyanide leaching. Following feasibility studies, a new process plant which included grinding mills, leaching, and adsorption tanks, thickener, desorption and gold roam facilities was constructed.

Jan 1, 1989

The Martha Mine is an open cut operation situated in the midst of Waihi town which has been operating since 1987. Since then it has produced some 700,000 ounces (oz) of gold and 4,000,000 oz of silver from an epithermal vein system. It was previously worked by underground methods from 1880 to 1952 to a depth of 600 m producing 5 million ounces (Moz) of gold and 30 Moz of silver. The licensed reserves are scheduled to be mined out early in the year 2001. An additional economic resource of over 750,000 oz of gold has been identified which can be accessed by deepening the pit a further 50 m along the main Martha vein. This would extend the mine life to the year 2007. Applications were lodged on 4 July 1997 for the necessary resource consents, discharge permits and variations for the current Mining Licence conditions. The extension project requires approval from the District Council, Regional Council and the Ministry of Commerce. The consent and permitting process is extensive because of the urban setting of the mine. An approach to keep the extension as similar as possible to the current operations was adopted to give the community and authority confidence in the proposed extension. This paper summarises the extension detail and the permitting requirements it has had to address despite the extension being "more of the same". The permitting process has been exhaustive with little recognition of the standards already achieved in protecting the environment which are recognised worldwide.

Jan 1, 1997

Boliden's Aitik open pit mine located in northern Sweden, will expand yearly production from 18 to 36 Mt of copper ore during 2010. The expansion includes a new concentrator located 3 km off the pit, two new apron feeder crushers connected to the ore storages and concentrator with conveyors at a total length of 7 km. The concentrator has two lines with autogenous grinding mills and flotation each with a capacity of 18 Mt. Consequently the mine operation has to be expanded. To achieve this, there was several parallel processes ongoing; investments in new equipment, reorganisations, improvement projects in maintenance and productivity. The Aitik 72 project was started to coordinate productivity and mine planning activities. Initially the long-term strategic mine plan called for a total movement of ore and waste to increase from 40 to 72 Mt but has today increased to 89 Mt. Productivity projects have been focused on load and haul activities such as fuel economics (Renstr÷m, 2007), effective utilisation of trucks partly by increasing manning levels, improved dispatch and shovel utilisation focusing on optimal use of loader/truck fleets. The eco-driving projects previously reported have reduced fuel consumption significantly. This project is also a productivity project, as part of the fuel savings comes from minimising idle engine hours due to queues, break-downs, operator shift changes, etc but also from under and overloading. Effective use of truck fleets, ie transport of material, loading and dumping, thus excluding non-productive engine hours has been an essential motivator when deciding the size and number of new trucks required. This has resulted in a reduction of the investment with at least one but maybe two trucks. A third major project was to optimise shovels together with truck fleet by improving short-term, up to two weeks, detailed planning of drilling and shovel activities. Daily scheduled breaks for maintenance as well as planning of shovel utilisation, down to shift level are included in the production plans. KPIs and online production reports, based on real-time monitoring of drill rigs, shovels and trucks, have been an essential tool used regularly to engage and motivate mine production personal and information reporting to management. Several projects have already reached their goals. The projects will continue throughout 2010 to ensure that productivity targets are met.

May 1, 2010

By M Denton, M Rheinlander, S Mundell, M Broadgate

The manufacturing industry reinvented its approach to the manufacturing process by managing and measuring it end-to-end. This improved returns on production assets, improved information quality and reduced delivery time, resulting in larger net profits through cost reduction and improved cash flow. Today this approach is standard in the manufacturing industry. Resource development has many requirements in common with the manufacturing production line. These include: control of the various steps, transparency of the state of the process to various levels of the organisation and the overall efficiency with which the process is executed. The authors argue that the introduction of manufacturing execution systems (MES) concepts and technologies to resource development processes will lead to similar improvements in control, transparency and efficiency and could improve profitability and enable staff to work more effectively and make better decisions.

Jan 1, 2009

Long-range side-scan sonar and conventional geophysical data for the Peru Trench region (8`S-15¦S latitude) have been analysed. The data show that the Peru Trench is a site of sediment subduction where bending-induced normal fault-ing of the Nazca plate plays a key role. The sediments are continually removed from the trench axis region by their inclusion in normal fault-defined void spaces, such as grabens. In the process of subduction, the sediments are often offscraped, folded arid kneaded temporarily at the base of the shoreward trench slope. The subduction complex comprising such sediments is narrower than 20 km and its volume remains more or less constant due to regular removal of its contents along with the down-going plate. Addi-tionally, morphology of the subducting Nazca plate is responsible for subduction erosion of the South American plate, where the horst blocks cause tectonic erosion by abrasion and the grabens provide a mechanism for removal of the eroded material.

Jan 1, 1990

By X Y. Ma, X G. Tian, P F. Zhang, T B. Zhao, Z H. Li, Z Y. Fu

This study analysed the fracture characteristics and movement process of goaf roofs under the condition of gangue backfilled mining, based on the engineering conditions of Tangshan Mine F5001 gangue backfilled working face. The inclined borehole detection method is adopted to conduct long-term and fixed-point detection of the roof stability. The distribution characteristics of mining-induced cracks in the roof are described quantitatively based on the crack density, and a similar model test method is used to assist the analysis of the roof movement under the control of gangue backfilled mining using stress sensors and digital speckle deformation field monitoring. The results show that under the condition of gangue backfilled mining, structural cracks in the roof typically appear at the boundary of rock strata. The appearance of cracks is related to the rock strata where they are located. Structural cracks appear in the form of single cracks ahead of the working face and develop into structural cracks in the goaf. The roof movement of the coal seam develops in five stages: fracture incubation, crack extension in advance, dense fracture development, steady fracture expansion, and roof stability. Separation forms the primary component of the roof subsidence, accounting for more than half of the subsidence value. The separation generally extends over a long distance along the strike, and vertical crack-intensive areas appear in the roof above the cut-off and stop line. The findings of this study provide a theoretical basis to support designs of backfilled mining and upgrading of hydraulic supports in working faces.

Nov 29, 2022

By Skaviniak M

Some better perspectives applying to the exploitation and dressing of polymetallic ores in the Banskfa. gtiavnica-Hod- rusea Ore District are supposed to be achieved after a suc- cessful investigation and proving there the existence of deep-seated mineralization as well as due to increasing de- mand for non-ferrous metals and consequently to higher mar- ket prices of those recently noticed. With respect to the present situation in mining and to the further technical development as well, a several times higher exploitation may be in this region expected, especially in the deeper .eated parts of the deposit. When solving the tasks of a complex economic exploitation over the whole region, consi- derable attention is paid to regional relations and impact studies (due to expected exploitation and ore dressing but also to very difficult problems of dewatering (drainage pro- blems-). It will be first of all necessary to find there an equilibrium between the consequences resulting from the re- naissance of mining industry and environmental requests un- dispensable for the city of Banska 9tiavnica and the other neighbouring towns in the vicinity of mining plants.

Jan 1, 1988

By Howell M. W

The purpose of this paper is to outline the main points in the construction of the various types of wire ropes more commonly used for winding in Australia; and the maintenance of the ropes, and cage and skip safety gear as practised at the South mine, Broken Hill.It should be mentioned that both of the shafts at present in use are dry, and both downcast with or without the assistance of the two exhaust fans normally in use: Night shift and week.-end overtime are practicaly non-existent.Thus, during night shift, the cages in No. 7 shaft are landed on the chairs at the surface, providing efficient covers for the· shaft, and allowing the maximum amount of rope to be wound on to the drums. This also applies to the cages of both No. 7 and No. 4 shafts during the week-ends.These factors, combined with electric winding and skip haulage, are calculated to obtain the best use of the ropes when properly attended.WINDING ROPES-TYPE AND CONSTRUCTIONThese ropes may be divided into four main types which will include the more commonly used constructions(a) One-size strand.(b) Warrington strand.(c) Flattened strand.(d) Locked coil.1. One-size strand as the name implies, is a rope the strands of which are constructed 9f wire of the one size.Usually the strands are of 7, 19 or 37 wires.

Jan 1, 1940

By P Pelletier, J Tessier, C Duchesne

This paper summarises research into the study of the control of flotation processes based on froth images. A review of the froth flotation operation background and the relevance and role of the froth phase are presented. The use of numerical image analysis techniques for the extraction of significant patterns from industrial flotation froths is discussed. First, the froth was analysed by the use of the multivariate image analysis (MIA) method to extract the spectral variation contained in a RBG image. The partial least squares (PLS) method was applied to develop an empirical model for the prediction of froth grade. The results of this application are illustrated using an industrial case study. Second, the froth was also analysed by grey-level co-occurrence matrix (GLCM) and wavelet transform analysis (WTA) to extract features related more to morphological aspects. Since there is useful information hidden in froth texture, these methods are used as texture descriptor to classify different types of froths. They also provide qualitative information on the changes in the visual appearance of the froth. The pros and the cons of those methods are highlighted. Third, a control strategy based on a froth structure indicator was developed and implemented on an industrial zinc flotation circuit. The feedback controller uses the reagent flow-rate in order to maintain the froth structure at its set point. Process improvements obtained from the implemented control strategy are highlighted. Finally, the feasibility of implementing a hybrid control strategy consisting in a froth structure supervision controller based on the froth concentrate grade estimated by MIA and recovery inferred by image analysis is discussed.

Jan 1, 2005

By R Atmuri, W Liang, R Prasad, Y Liu, E Wingate

Yellow phosphorus (YP) has been commercially produced since the 1920s. First in the USA by the Tennessee Valley Authority (TVA), next in Russian (Kazakhstan) in the 1950s, and finally in China in the late 1970s and early 1980s. There are operations in Vietnam and Sarawak on a smaller scale. YP has become very in vogue due to its use in the production of lithium iron phosphate battery cathode precursor materials by the Chinese and other western battery manufacturers. The YP is also used to produce purified phosphoric acid and higher grades of acid using a thermal oxidation process after smelting. This paper will look at the basics of the smelting including slag chemistry, alloy chemistry and offgas chemistry. The paper will look at the design of the furnaces used in the YP production process as well as the downstream recovery of phosphorus from the smelter off-gas stream to YP. The next part of the discussion will focus on the operations of a YP smelter with regards to control of the furnace to optimise phosphorus recovery to YP. Will discuss tapping cycles for alloy and slag with a view to optimal phosphorus recovery. The discussion will close out with a review of operational challenges in the smelter and a brief description of the downstream conversion of YP to high purity phosphoric acid.

Aug 21, 2024

Selective continuous surface mining is a rapidly developing system of mining which will have a significant impact on many present and future open cut mines. In many aspects the technology is in its infancy, whilst in other facets concepts drawn from other sectors of engineering are well proven. Full development of the potential and benefits of this technology will only be achieved if the mining companies and manufacturing companies work together to produce machines which the end user really wants.

Jan 1, 1986

Krupp Polysius AG, FRG, in close cooperation with Prof. Dr. K. Schoenert, FRG have developed the principle of the high pressure grind- ing roll POLYCOM. The POLYCOM mill basically consists of two counter-rotating rolls of large diameter and relatively small width, one of which is fixed and the other moving in slide blocks. The pressure required for comminu- tion is applied via the sliding roll by a powerful hydraulic system. The comminution takes place between the rolls under high pressure in the bed of material by nipping and compacting. The top feed size-depending on the rolls diameter -may be as coarse as conventional secondary crusher feed and the product is a compacted cake containing a high amount of fines created by micro-cracking. The amount of fines depends on the pres- sure (grinding force) applied. Operating results show that even in wet griding circuits capacity increases at downstream connected grinding mills of up to 100010 can be accomplished with an interconnected POLYCOM machine and energy savings of up to 25070 may be achieved depending on application. POLYCOM can be used in existing grinding plants for low-cost upgrad- ing of capacities but also as an advanced alternative to conventional crush- ing and grinding equipment in open or closed circuit configuration. A single industrial size 2.8m roll diameter POLYCOM machine may be fed with top feed size of up to 200mm and produce a finish product as fine- grained as known from rod and ball mills but with less energy consumption. Meanwhile, the POLYCOM high pressure grinding roll has established itself world-wide in the cement industry and is now entering the mining industry. POLYCOM machines are currently designed in industrial standard sizes of 1.0m to 2.0m rolls diameter and drive units of up to 2400 kW. This paper includes: principles of high pressure grinding, main fea tures of the POLYCOM machine, results of tests on various materials including Australian gold and copper ores carried out at the POLYSIUS research centre in Germany. Some examples of industrial applications of high pressure grinding will also be presented.

Jan 1, 1988

The Callie Underground Gold Mine (Callie) is owned by Newmont Asia Pacific and located 531 km north-west of Alice Springs in the Northern Territory. Historically, stopes have been mined utilising a primary and secondary stoping sequence with cemented aggregate fill and rock fill respectively. Current and near-future mining will employ long hole open stoping with rib pillars and rock fill with a paste fill system approved to allow a higher extraction ratio from mid-2011. The Callie rock mass is of good quality with little or no mining difficulties during development and stoping to a depth of 1140 m below surface. Development is currently occurring at depth of 1360 m below surface. Stress damage previously observed only in secondary stope accesses is now observed in development unaffected by stoping stresses. A change in rock mass properties is being experienced with depth, with more pronounced and frequent joint planes. Also, other structures are intersected more commonly, such as lithological boundaries and fault zones. The 'Callie rock factory' mentality that has persisted for years is challenged. This paper covers an appraisal of the stress and ground condition changes at Callie. The appraisal outlines the mine design criterion that was developed and examines the transition from a low stress environment to one where stress damage is observed. Discussion includes a judgement on the rock mass damage observed in development, the dominant geotechnical factors influencing the change in ground conditions, and if a correlation can be made between the observed rock mass damage with stress through the use of numerical modelling.

Nov 25, 2010

Underground measurements, observations and computed simulations, started a long time ago were concerning the study of : - occurence of typical rockburst, - inducing, stretching of main fractures in the roof of caved longwalls. They made obvious a foundamental phenomenon of inducing of strata fractures involving contact be- tween two layers quite different in their elastic characteristics : coalseam and rocklayer.. The start of primary cracks in maximum abutment zone takes place in the rock near the contact surface. It is opening of crevasses induced by traction stress component resulting of difference of rigidity of both materials and no sliding on in- terface. Occurence and stretching of these crevas- ses are a rheological phenomenon so that the rate of advance and stops of the face influence the distance between the crevasses and the stretching of these ones. The characteristics of these cracks in space and time affect mining conditions. So it is for fractures proximity and expan- sion inducing eventual blocks formation in longwall roofs in front of faces, for depth and delay of road- ways ribsides fracturing, inducing some rockbursts. In longwalls roofs, cracks initiated in front of a face can be either quite close or quite distant each from the other one, according to the depth of crushed coal in front of the face, which af- fects also extension of the cracks.

Jan 1, 1988