Search Documents

By M Simanjuntak, A M. Supomo

PT Freeport IndonesiaÆs copper/gold operation disposes of approximately 222 000 dry metric tonnes of tailings per day via two thickeners. Reduction of the flocculant dosage rates in each of the tailing thickeners has been achieved with the installation of Clarometers«, modifications to the existing operating DCS control strategy and a change in plant flocculant. This has reduced the flocculant consumption rate in the last twelve months by approximately 20 per cent. It has also highlighted the disparity in the settling rates of the two thickeners. Collaborative efforts between Cytec technical site engineers and Freeport operational personnel have made possible the overall gains achieved in the tailings thickener optimisation.

Jan 1, 2003

By T J. Howard

At BHP Billiton Iron Ore operations, run of mine ore from the several Newman Joint Venture (NJV) mines is railed in 12 kt rakes to Port Hedland. Rakes are processed sequentially, with the lump and fines components from each rake sampled after crushing and screening. The grade of ore from the individual mines varies around consistently different means. Although a discrete sample is attributed to each rake, the sample contains some material from the following and/or the preceding rakes due to dilution by ore from the neighbouring rakes during the dumping, screening and crushing processes. Individual rake grades at the port are therefore biased according to the mine sources of adjacently processed rakes. Dilution does not affect the grade of the overall NJV product or the accuracy of port stockpile grades; however, it does limit the ability to use port rake grades to review the quality performance of individual mines and provide meaningful lump-fines algorithms and port to mine biases for individual mines, information that is useful when scheduling ore for mining. A non-linear regression model has been used to estimate the average dilution from the preceding and following rakes. It has been shown that the lump and fines samples for 12 kt rakes are each diluted within the Port process with about 8.3 per cent of the sample coming from the preceding rake and about 3.6 per cent from the following rake. This can bias the reported rake grade by up to one per cent iron. The results of this analysis have been incorporated into the daily grade scheduling system to provide more accurate individual mine grade data and consequently better decision making.

Jan 1, 2007

Downstream value-adding is a strategic issue for a country like Australia, which has a resources-driven sector of a scale that has significant impact on the national economy. The question of why producers are not doing more to ævalue-addÆ is often asked. In Australia this debate takes place within the context of: an era of unprecedented growth in demand for resources driven by the rapid urbanisation of China, India and others;impending legislation and uncertainty around carbon pricing;rapidly rising energy costs;significant supply-side shortages including infrastructure, skills and manufacturing capacity; andsignificant industry consolidation of primary resource producers with commensurate improvements in market power.There are several examples of resource-based industries which have developed their business along the complete value-chain; for example large oil and gas producers successfully span upstream and downstream operations including refining and petro-chemicals as well as retail distribution of fuel and other products. Relevant frameworks that provide insight and understanding into the strategic issues around value-adding are reviewed and examples of the application of these frameworks to companies and industries which have successfully adopted a strategy of integrating along the value-chain, as well as those players who have focused on parts of the value-chain are presented. The issues around value-adding in Australia are then reviewed with reference to these frameworks and it is concluded that the issue is a conflict between the objective companies who wish to maximise financial value versus the desire of governments to increase economic benefits. An approach to aligning these objectives is proposed.

Jan 1, 2008

By P Walton, L W. Armstrong, D P. Blair

Sydney is the capital city of NSW and has a population of approximately four million people. Eighty per cent of the cityÆs water is supplied by Warragamba Dam, which is situated some 75 kilometres south west of the city centre. A risk assessment was carried out on the dam and future predictions of water flows into the catchment area showed that there was a risk of a one in 700-year flood not being contained by the dam. The predicted loss of life and property damage warranted the construction of an auxiliary spillway on the eastern side of the existing dam to cater for any uncontrollable influx of water. A test blasting program was instigated and the blasting parameters were established that would lead to routine production blasting of the sandstone rock making it more cost effective to excavate. Blast induced vibrations were a concern to the owners and the dam wall and ancillary infrastructure was instrumented with sensitive vibration monitoring equipment during the test blasting phase of the operation. Once the blasting parameters were established from the testing program production blasting was carried out on a daily basis to maintain æstockpileÆ of fragmented ground for the excavation equipment. Blast vibration models were developed to predict vibration levels for more sensitive areas of the dam to give the operators more confidence in their operations. The blast induced vibration levels recorded did not cause any structural damage to the dam wall and the waveform frequencies of the blasting operation were much higher than that experienced during a recent earthquake. The integrity of the SCAÆs assets were at no time jeopardised.

Jan 1, 2001

The resource sector is conservative industry and people are resistant to change. The methods and procedures used to implement changes in process plants ultimately determine the success of such changes. The financial managers have a large say in where money is spent and the technical personnel must justify the cost and benefits for any expenditure. There are also others who believe it canÆt be done û æwe tried thatÆ. Implementing change needs a æChampionÆ who can assess the risks, plan, define the objectives and scope, set the goals, determine the key performance indicators (KPIs) and stay focused. This also requires preparing a budget and schedule and measuring against this. Contract management, reports and reviews are part of the implementation. Several case studies are given as examples of the implementation of process design changes to highlight the critical aspects involved.

Jan 1, 2009

By Somerville M, Muray A, Bocking M

Australia has an extremely large total hot dry rock (HDR) resource above a depth of 5 km, equivalent to 7500 times its present annual energy consumption, of which 80 per cent underlies the Great Artesian Basin. The resources most likely to be exploited first are those residing in homogeneous granitic bodies beneath sedimentary basins containing insulating rocks such as shales and coal measures. In the Sydney Basin south of Muswellbrook, an area of high geothermal gradient corresponds to a gravity low thought to be a buried granite body at a temperature of possibly 250¦C. This locality is suspected to have the ideal geological characteristics for Australia's first hot rock test facility. Australia's high HDR potential is possibly unique in the world, in that the potential sites satisfy four independent, geological conditions, each considered as favourable for the creation of a resource, and for the ease of extracting that resource. They are: ò Higher crustal heat generating capacity than that of normal continental crust. ò Much of the Australian continent is covered by sedimentary basins which contain a high proportion of shales and coal measures that have low thermal conductivities, thus providing an insulating blanket for the heat being generated beneath. ò The sedimentary basins are in many places underlain by large untectonised granitic bodies that are not only a major contributor to heat generation, but also ideally suited to the establishment of HDR reservoirs. ò The crustal shortening stress field that is found in the majority of the Australian continental crust results in a vertical minimum principal stress orientation which should result in the development of favourably oriented horizontal stimulation cells necessary for maximising an HDR resource.

Jan 1, 1995

A thousand writers have harped upon the wondrous nature of the inventive faculty. They realise that man is a creator, and that capital and labour alike are, and will always be impotent without machinery and processes that is invention. What Bacon has said is echoed by them all, "the introduction of new inventions seemeth to be the very chiefest of human actions. The benefit of new inventions may extend to all mankind-they make all men happy without injury to 'any' they are new creations and imitations of God's own works." My remarks will occupy another field I will refer to some of those features of the Patent Laws of different countries, which prevent the use of new inventions, oppress the development or inventive' genius, and diminish human happiness and progress' Wherever Patent Laws are framed and administered upon wrong principles, these results are inevitably found. A concise, complete, common-sense comparison of the chief Patent Laws of the world cannot easily be found but to avoid seeing scrappy, misleading references to Patent Law in the press particularly the English-would be equally difficult. Writers who are considered authorities so frequently make minor issues prominent and so uniformly fail to give weight to fundamental principles that the effect on the public is to mislead.

By C Smith, D Lilly

The Lafarge Marblehead Plant in Marblehead, Ohio, USA produces 4.2 million tonnes of sized aggregate yearly. In 1997, a program was instituted to maximise primary crusher productivity through the optimisation of blasting variables and procedures. A proprietary blasting shot report database and the Lafarge production database was statistically analysed to provide guidance in the program. Blasting powder factor (kg/m3) was the main control variable utilised to increase crusher throughput. In 2005, the program was refined to increase the production of certain high margin aggregate sizes and the reduction of fines. The principal blasting component affecting the percentage of high margin size production appears to be pattern area (burden and spacing area). This can be coupled with powder factor to optimise the production rate of high margin aggregate sizes. The size optimisation program incorporates the blasting shot report database, Lafarge production database, statistical analysis and aggregate sampling. A preliminary indication is that the production of high margin sizes (12.7 mm X 4.8 mm, 24.4 mm X 12.7 mm, and 50 mm X 25.4 mm) has been increased seven to 12 per cent utilising these techniques. As an added benefit, blasting costs have been reduced linearly as burden û spacing pattern areas have increased and powder factors have decreased. The program is ongoing and will investigate other blasting procedures and variables including electronic blasting caps to further increase the production of high margin products. The statistical methods involved in the analysis are described in this article for use in other mines and situations. The methods described can be used to optimise crusher throughput, digging rates and product size.

Jan 1, 2007

Just as Australia is part of the Pacific Rim, so the Pacific Rim should be viewed as part of the whole world. That applies in particular to that scarce commodity û money. There are five main factors of production in any mining development û mineralisation, materials, manpower, management and money. LetÆs focus on the upstream input û mineralisation, and the downstream input û money, especially in the area of communications. Unknown to many, the Competent Person reporting on Mineral Resources and Mineral Reserves has a direct and unavoidable impact on the companyÆs financial statements û the profit and loss account and balance sheet. With respect to reporting of the major asset of most mining companies û the resources/reserves û investors are getting a better deal now than at any time in memory as regards flow and adequacy of information. Australia has been a world leader in this regard. The outlook is for even more informative and useful reporting. The more rigorous reporting requirements for Exploration Results and Mineral Resources/Reserves, which have become a worldwide phenomenon over the last five years, will continue. This will be positive for the mining industry as a whole and for Australia in particular. However competition for the scarce investment dollar will also increase. Put simply, mining has many competitors, unconnected with mining, for the capture of the investment dollar. It behoves all participants to recognise that there are three investment factors which influence strongly the willingness of investors to put money into mining. These are Confidence, Credibility and Consistency. AustraliaÆs investment image stands high in these three respects, but the competition will continue to grow. AustraliaÆs lead must be maintained. However, some investment decisions should not necessarily be based on fundamental, quantifiable facors. Some of these are outlined.

Jan 1, 2004

By D Landriault, G W. Wilson, L Langetine and

Engineered soil covers are used for final closure options for both waste rock and tailings disposal facilities. Currently, cover construction requires excavation of appropriate cover material from a nearby site. If no suitable materials are available, the mine operation may have to ship appropriate materials long distances to the site before the construction of the cover can even begin. This has led to the proposal to engineer cover materials using existing waste materials from the mining operation. The paper presented here describes the results of a laboratory scale testing program to evaluate the potential for blending waste rock, smelter slag and tailings for the creation of a suitable cover material at a site in Canada. Tailings from the local mill, waste rock and slag were collected in the field and blended to create a material with an air entry value similar to the tailings and with physical strength similar to the waste rock. Testing indicated this mixed material could be blended at a consistency of a paste and was suitable for pumping. It can also be compacted to a high-density material. The preliminary results show that it may be possible to blend waste rock, slag and tailings into a material that can be utilised in the construction of a water retaining cover.

Jan 1, 2003

Welcome to this 13th Congress of The Council of Mining and Metallurgical Institutions. It is twenty one years since The Australasian Institute of Mining and Metallurgy last hosted this congress and it is a privilege and a pleasure for The AusIMM to have that responsibility once more. The theme of this congress "The Twenty-First Century - Mining for Mankind" stimulates many thoughts. The first thought that it generates in me relates to the reference to the 21st Century. We are still 14 years away from it and already consideration of the beginning of the next millenium is becoming something of a cliche. If we feel like that about it now, how will we feel at the 14th Congress of the CMMI in 1990, or the 15th in 1994 or the 16th in 1998? If we do all the crystal ball gazing about the 21st Century this week, those poor devils in the 1990s will in fact have nothing to talk about. Of course that is not the case. This is a very appropriate time for those of us concerned with mining and metallurgy to contemplate the next century. Fourteen years is about the extent of forward planning necessary in the mining business. I sometimes feel that most people do not take seriously the need for long range planning in our industry. Politicians, investment fund managers, and others under severe short-term pressure to perform in our hyperactive world may nod in apparent appreciation of our long term plans but their actions in the interests of expediency often betray-them.

Jan 1, 1986

By D E. Langberg, J S. J va, D R. Swinbourne

Specifications on the types and levels of impurities tolerable in metals are becoming increasingly stringent, and are pushing the limits achievable with conventional refining technologies. Particularly difficult is the removal of electrochemically noble elements with low volatilities, such as copper, from more active host metals such as lead, iron and aluminium. Electrochemical refining, utilising the ability of certain solid electrolytes to selectively transport copper or other impurity cations away from the molten host metal into a separate refining phase, may provide an answer to this problem. Numerous studies on solid electrolytes used in concentration sensors have been reported, as well as a limited number on metal refining. Oxygen anion conducting solid electrolytes have been applied to the deoxidation of copper and steel while cation conductors, eg ¯ -alumina and Nasicon materials, have been used to remove lithium and sodium from aluminium. However, solid electrolytes have yet to be applied to the removal of noble elements. The behaviour of solid electrolytes under the extreme conditions of molten metal refining is not well understood. This paper will examine the potential use of solid electrolytes to remove noble metals such as copper from active host metals such as iron. The suitability, and selection criteria of available solid electrolytes for implementation in the metal refining industry in the future will be discussed. In particular, the stability of Cusicon, a copper superionic conductor potentially suitable for use in metal refining, has been assessed and the results of the experiments are presented.

Jan 1, 2000

By A He, J Li, J Pan, J Clout

The removal of sulfur from SO2 containing flue gas is improved by adsorbing SO2 into solution with manganese ions as catalyser, however, burnt lime slurry has to be added to modify solution pH and the CaSO3 by-product is of low economic value. In this paper a novel one step process for simultaneous manganese leaching-desulfurisation of flue gas is presented. An investigation of the effect of process parameters included flow rate and SO2 concentration in flue gas, adsorbing time, solution to solid mass ratio, leaching time, and their impact on the oxidation and removal of SO2 from flue gas. The catalysing mechanism of manganese ions on the oxidation and SO2 removal was demonstrated by calculation of the species originating from manganese ions and SO2 in the solution according to solution chemistry. SO2 removal in the adsorbing solution took place at pH 5 - 6, where manganese ions dominantly occurred as Mn2+, and the chain reactions for oxidation of SO2 starting from HSO3- were improved by the presence of Mn2+. SO2 bearing flue gas was effectively desulfurised by leaching rhodochrosite (MnCO3), with desulfurisation of the flue gas and modifying the solution pH being achieved simultaneously, and MnSO4 of high economic value recovered from the leachate. 85 per cent manganese leaching and over 70 per cent desulfurisation of the SO2-bearing flue gas were achieved with only one adsorption stage under optimum conditions.

Jan 1, 2004

By P Cameron

Many products and technologies have been developed from outcomes of research projects carried out by the Julius Kruttschnitt Mineral Research Centre (JKMRC). When these products and technologies are applied to the design and optimisation of blasting, comminution and separation, improvements in profitability can be realised. In 1970 Alban Lynch promoted two practical ideas to improve plant operations: Ore and equipment properties can be separated allowing experience with one type of ore or equipment to be transferred to other types of ore and equipment. If this experience was encapsulated in a mathematical model, then these properties could be combined and used to simulate (ie to design and to optimise) complete mineral processing circuits. Many problems associated with scale-up from laboratory to industrial equipment could be eliminated by experimental work on full-scale equipment in the plant. Many JKMRC research projects have focussed on the development of models of unit operations in mineral processing and their application to process simulation. Models of comminution and classification developed at the JKMRC have been used since the early-1980s. Ore characterisation techniques developed to support these models are licensed world wide through JKTech. The application of comminution modelling techniques to blasting, which optimises the process feed size distribution is used in Mine-to-Mill? projects. The advances in the understanding and modelling of froth flotation over recent years have provided the opportunity for integrated ore characterisation and process optimisation from resource to product. JKMRC project outcomes often provide proven opportunities for the mineral industry to improve performance and productivity. JKTech was established in 1986 to commercialise and market the most promising outcomes and thus ensure their continuing availability to the mineral industry. These include: commercial software (JKSimMet, JKSimBlast and JKMetAccount); monographs (Comminution and Blasting); technologies (Mine-to-Mill? and flotation optimisation); and hardware products (JKFrothCam, JKJetLift? and the Mineral Liberation Analyser). This paper summarises these technologies and their benefits.

Jan 1, 2002

The earliest caveman, very much a minority group, in the face of great adversity and person- al peril, had to take his livelihood by stealth or force of arms - aided by some degree of reas- on and ingenuity. He was pretty much a law unto himself. As time went on, his type became more numerous; and, after bumping heads with the- tough bloke who lived in the cave across the valley, he decided that perhaps he ought to try to get along with him. Perhaps he could trade some over-ripe emu meat for that `roo skin that he had tried to take. Then too, next time he wants a woman, he had better use a lighter club and just stun her a little - that last one was pretty badly bashed. Perhaps he should keep her around the cave and train her to keep the fire going, gather some roots, and skin the game. Those joeys of hers are kind of cute too. Of course they eat, and it would necessitate bringing in more food. So man gained increasing responsib- ilities to his family and neighbours. He domesticated animals, learned that he could cultivate certain plants that were palat- able and would supplement the meat diet, and found that he could modify earth materials to make tools - he became a grazier, a farmer, a miner and a manufacturer. He ceased to be nom- adic and community life came into being. This complicated life and made more rules essential.

Jan 1, 1974

Oxy-ACETYLENE system of welding and cutting is at present practised in two forms, which may be described as the high and lowpressure systems. In the high-pressure system the two gases, oxygen and acetylene, are delivered. to the blow-pipe under pressure from properly constructed trade cylinders. Oxygen cylinders are in two sizes, each containing 100 and 200 cub. ft. of gas respectively. These cylinders are charged to a pressure of 120 atmospheres, or 1800 lb. per sq. in. approximately. The acetylene cylinders are made in one size as far as the writer knows, and contain 200 cub. ft. of acetylene gas at a pressure of 10 atmospheres. Each cylinder is provided with a valve and connection for attaching a regulator to "break down" the high pressure in the cylinders to the necessary low working pressure of the blow-pipes, and to deliver the two gases at a constant pressure irrespective of the variable pressures in the cylinders. These regulators can be adjusted down to as low as 1 lb. and are provided with two pressure gaugesone reading the contents of the cylinder in atmospheres, and the other the working pressure in lb. per sq. in. The high-pressure, or "two cylinder" system is compact and can readily be transported from place to place in the works. For this purpose the two cylinders are mounted on an easy-running 4-wheeled truck, which the operator and assistant find no difficulty in manipulating. In the low-pressure system the two gases are delivered to the blow-pipe, one from the oxygen cylinder and the other from the acetylene gas generating plant, which consists of the following:Generating cylinder, half filled with water, into which the cathoide is plunged. The generated gas is passed through a filter to the gasometer, then through a water washer on to the hydraullic seal...

Jan 1, 1922

This paper presents a review of heat illness in mining, including reference to several recent investigations by the author. Heat illness is a collective term, covering the conditions of heat stroke, heat exhaustion, heat cramps and miliaria rubra. Heat stroke is life-threatening and is by far the most serious condition. It is rare in mining, if appropriate control measures are instituted. Heat exhaustion is primarily due to hypohydration, following prolonged sweating in hot conditions. Symptoms include fatigue, headaches, dizziness, anorexia, nausea, vomiting, shortness of breath, or brief syncope. Confusion, ataxia, prolonged unconsciousness or convulsions are strongly suggestive of heat stroke. Heat cramps are painful involuntary contractions of skeletal muscle associated with work in hot conditions. The limbs are usually involved and the spasms typically last a few minutes, during which the affected part of the body is incapacitated. Heat cramps tend to occur in heat exhaustion, when hypohydration becomes marked. Miliaria rubra is a skin rash caused by extravasation of sweat into the skin, as a result of obstruction of the sweat glands. It occurs after prolonged and profuse sweating in hot environments. It can take three to four weeks of sedentary duties, in an air-conditioned surface environment, for the condition to resolve. Heat illness would be unlikely in underground mining, if the thermal environment was sufficiently well controlled by ventilation and refrigeration. This is however, often not practicable. Where engineering controls alone cannot provide sufficient control of risk, the residual risk can be assessed using an appropriate heat stress index. While procedural controls may further reduce the residual risk, it is important to remember that these are less reliable than engineering controls and cases of heat illness may still occur. Procedural controls include the application of heat stress limits, education, hydration, self-pacing, early symptom reporting, medical advice, acclimatisation procedures, air conditioned accommodation, support to achieve a healthy body mass index, and an effective emergency response capacity.

Jan 1, 2005

The impulsive loading tests under confining pressure were performed to investigate the dynamic fracture properties of rocks in a triaxial stress state. The apparatus in this study consists of the Split Hopkinson pressure bar, a pressure vessel and hydraulic actuator. Magnetite-quartzite and limestone were selected for the test. The stress-strain curves and fracture strength under confining pressure obtaind in the tests were compared with those of the conventional triaxial tests. Finally it is concluded that on the effect of dynamic that on the effect of dynamic compressive strength of rock, dynamic elastic coefficient of rock and confining pressure etc. on the blasting result

Jan 1, 1990

By O K. Paki

A 14/12 millMAXTM pump was installed in the SAG1 grinding circuit as a trial replacement for the existing 12/10 Warman for performance comparison and in an attempt to overcome process difficulties. Krebs Engineers have developed the millMAXTM pump wet end to adapt to a variety of power frames. This system has been developed specifically for coarse material contained in mill discharge. SAG1 discharge screen undersize with a top size of 10 mm is collected in a flat bottom sump. Two 12/10 Warman pumps located on the same side of the sump, pump the screen undersize at 50 to 65 per cent solids to a distributor box which splits into two separate ball mill circuit sumps. One pump is installed towards the screen feed, while the other is towards the screen oversize discharge. The pump located towards the screen oversize discharge is prone to continual operating problems including pump bogging, high impeller and casing wear, and has consequently restricted SAG mill throughput. To rectify this pumping problem, it was decided to change-out the wet end of this pump with a millMAXTM. The design of the new pump enabled the wet end only to be retrofitted to the existing Warman pump frame, thus reducing change-over time. This was undertaken in the workshop under the supervision of a company representative where the pump, complete with bearing frame, new wet end, motor and base frame, was assembled. After installation of the millMAXTM pump during a SAG mill shutdown, performance indicators including motor power draw, sump level, and pump discharge pressure have been monitored. The trends indicate an increase in discharge pressure, low sump level, and low motor power draw. With the improved pumping efficiency there has been minimal pump bogging and no consequent SAG mill throughput restrictions. Pump wear rate has also decreased.

Jan 1, 2000

The GDR has extensive lignite deposits at its disposal, which formed the basis for the development of an independent energy source after 1945 and which will retain their significance well beyond the year 2000 (see fig. 1). In 1946 lignite output was about 110 x 106 t. In 1985 312x 106 t was produced and in 1988 the planned output will be ca. 315 x 106 t. Thus, the domestic produc- tion of lignite covers ca. 75% of the GDR's primary energy requirements. More than 80% of the electrical energy is gener- ated by the use of lignite and about 12% by nuclear energy. In addition to this, about 18 x 106 t/a mineral oil and about 6 x 109, m3/a natural gas are imported, predominantly from the Soviet Union. The lignite deposits of the GDR are of Tertiary origin and are recovered exclusively by opencast mining. There are two large regions (fig. 2): - in the region east of the river Elbe (Cottbus/Senftenberg- "Niederlausitz") and - in the region west of the river Elbe (Halle/Leip- zig/Magdeburg). These deposits differ in geological age and conditions of depo- sition, consequently there are differences in their chemical and physical composition and, thus, in their uses. The younger Mio- cene coals of the main region in the East of the river Elbe belong to the epirogenetic type and have a low content of ash and sul- phur. Among other things, they are suitable for the production of brown coal high-temperature coke (Lauchhammer and Schwarze Pumpe). The older Oligocene coals of the Halle/Leip- zig region are bitumenous in certain areas. Therefore, they form the basis for production in low-temperature carbonizing and chemical plants. In the Halle-Magdeburg region, where the lig- nite is in contact with the underlying Zechstein subdivision, so- called "salt coals" are found.

Jan 1, 1989