Search Documents

Capital expenditure on sampling and blending is often very difficult to justify. The costs are easy to estimate but the benefits likely to be obtained by constructing good sampling and blending facilities are generally difficult to estimate. For instance, improving blending of the ore feed to a smelter would improve throughput, yield and controllability ... but by how much? Similarly, better sampling would allow processing conditions to be dynamically adjusted and would improve extraction ... but by how much? Predicting benefits often requires the use of simulation models which carefully distinguish between true grades, predicted grades and observed grades. The parameters of these simulation models must often be estimated from rather inadequate information. These difficulties are illustrated using three scenarios.

Jan 1, 2005

By T Nixon

A common problem for many mines is insufficient total primary airflow or insufficient airflow in the correct places as the mine changes over its life. This has a number of impacts on the business operation and may result in the need for a major and unexpected capital upgrade of the system, cancellation of a planned production increase, reduction in production targets, increased operating costs, failure to provide contracted metals to customers or acceptance of substandard conditions in the workplace. In some cases, it can even result in premature closure of the mine. In recent times, higher metal prices have given an expected economic boost to many mines, potentially prolonging their life but simultaneously requiring the mine to develop to deeper depths or requiring assets such as shafts and fans to have their service life extended. Insufficient primary airflow is a particular problem in deeper mines as the ventilation circuits become longer, more convoluted, have higher shock losses and the actual airflow requirements increase due to a combination of leakage, dispersion of the workings and the problems of managing the additional heat loads due to higher virgin rock temperatures and autocompression. This paper discusses the reasons why mines experience unexpected shortfalls in primary ventilation capacity with its associated impacts on metal targets, profits and frequently on the health, safety and morale of the workforce, as well as its productivity.

Jan 1, 2008

By M P. Sandy

Some Western Australian underground mines are challenged by very high stress gradients. This environment frequently results in poor induced ground conditions and damaging seismic activity. In some cases, rockbursting or squeezing ground has been observed as shallow as 250 m below surface. Very few mines operating at depths greater than 500 m experience no stress-related issues. As a general result of this difficult environment, there are a growing number of mines that are now challenged or have been closed by induced geotechnical problems. Often, the up-front savings or perceived advantage of an inappropriate mine plan may be entirely lost to the real cost of managing the hazards, or a write-down of reserves resulting from access difficulties will diminish the economic position of the mine. From an engineering perspective, it is best if stress-related hazards can be proactively minimised, because reactive measures offer less improvement in risk exposure. In this paper, some examples of sequencing techniques for managing difficult environments are contrasted with examples from mines where developing hazards have adversely affected production or the economic viability of the project.

Jan 1, 2003

Cerro Matoso (CMSA) in Colombia produces ferro-nickel from lateritic ore containing approximately three per cent nickel, using a Rotary Kiln - Electric Furnace (RKEF) process, in which the calcining of the mineral within the kiln is second in importance only to the smelting of the mineral in the Electrical Furnace. This article discusses the installation and operation of an expert system to control the kiln of CMSA. In the CMSA process, the run-of-mine ore is crushed, homogenised, dried and mixed with a small percentage of coal, before being heated up to 900¦C in a rotary kiln in the presence of natural gas mixed with air in a controlled proportion (air/gas constant ratio). The final objectives of the process are the following: ò To reduce to a minimum the iron and nickel oxides in order to convert these into metallic ions; this is a reduction process to facilitate largely the smelting in the electric furnace. Since the reduction is made with natural gas, it is much more economical than the subsequent complete reduction in the electric furnace, since electrical energy is much more expensive by unit of processed mineral. ò To heat the mineral as much as possible to facilitate the subsequent smelting. ò To eliminate totally the moisture content of the ore. An expert system with fuzzy logic was commissioned in 1994 for the control of the kiln and it has operated with good results ever since.

Jan 1, 1996

In presenting size analysis data, one has the choice of various graphical techniques; each no doubt has been developed to highlight a particular aspect of the data. A frequency size distribution plot is used quite extensively to illustrate the importance of the finer size particles in iron ore granulation. However, the basis for such a plot is often not appreciated. As a result, cases of incorrect use can be cited. The aim of this paper is to extend the work of Alien (1981) and to provide, using examples and figures, a basic understanding of the implications of the various size distributions. A simplified method of presenting sizing data on a linear scale graph paper is presented and recommended. This involves a simple construction of a histogram of mass fraction versus particle size (in geometric progression).

Jan 1, 1992

By Tapp BA

Australia, considered an energy and mineral resource rich country, is poised on the verge of a major mineral industry 'boom'. It has been repeatedly emphasised that this growth in the mineral industry will form the basis of future economic development. Currently the mining and mineral processing industries use some 32% of the annual primary energy consumption in Australia. This share, although large even now, will increase with the realisation of the 1980's production expansions to 40% by 1985. Two metal industries dominate the energy scenario; iron and steel and aluminium. Major expansions in the local industry will be dominated by the aluminium industry. This highly energy intensive industry has planned major increases in metal production throughout the eighties. The implications of exporting cheap energy to pay for expensive oil imports, the ramifications on Australia's infrastructural ability to supply these major energy needs and the other options that might be

Jan 1, 1981

This paper discusses how the i-kon TM Digital Energy Control System may be deployed by miners of massive underground orebodies to deliver significant advantage in terms of safety, cost and environmental compliance. Digital Energy Control offers an exciting opportunity for mine operators to review their blasting and mining practice to gain the most advantage from this new technology.

Jan 1, 2000

By Longtin Z, Jin C, Zixin C

This paper proposes a new idea of disintegrating mode (division into simpler sub-problems) for complex problems, and based on -it, a study of the structure and the design of a knowledge base and inference engine for layout design of mineral concentrator expert systems. There is also a study of the formalisation method for describing the layout picture, and the work derived therefore found a formalisation method for expressing the knowledge and experience of layout design. There is also a study of the general characteristics of layout design knowledge.

Jan 1, 1993

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 T Kang, V Sahajwalla, L Lu

During devolatilisation, physical behaviour of coals was investigated in horizontal electrically heated furnace with an inert gas atmosphere, and gasification rates of four coal chars and coke were measured thermogravimetrically in a carbon dioxide atmosphere at temperatures in the range 1100oC - 1500oC. The volume change of chars was also measured in horizontal electrically heated furnace at various temperatures. Both reactivity and the activation energy for the gasification of coal chars were found to be strongly influenced by pore structure and the carbonisation conditions employed during preparation. CO2 reactivity of chars increases with increasing reaction temperature, and particularly increases more rapidly over 1300¦C. CO2 reactivity of coke is lower than that of non-coking coal chars in the range of 1100¦C to 1500¦C. CO2 reactivity of chars with smaller pore area and bigger pore diameter is less than that of chars with bigger pore area and smaller pore diameter. During gasification, the volume of chars did not change significantly at the lower temperatures of 1100¦C and 1200¦C, but at the high temperatures, 1300¦C to 1500¦C, the volume of chars quickly decreased due to ash softening and melting. The CO2 reactivities of the chars are controlled by the mixed control of chemical reaction and pore diffusion in the temperature range 1100¦C to 1300¦C, and by bulk diffusion in the temperature range 1400¦C to 1500¦C.

Jan 1, 2000

By O Otgonbayar, B Bayarmaa, D Batbyamba, S Amar-Amgalan, K H. Natsagdorj, J Nomin-Erdene, B Boldkhuu, T S. Sainzaya

The Argyle deposit in the Kimberley region of Western Australia was the world’s largest accumulation of natural diamonds. Following its discovery in 1979, the mining of associated alluvial diamonds commenced in 1983, followed by the pipe in late 1985. Over the life of the mine to its closure in November 2020, Argyle produced approximately 900 million carats of diamonds. Argyle diamonds are distinctive in having a predominance of brown colours and rare highly-prized pink diamonds, which are a signature of the deposit. The 3D geological model developed from mining and deep drilling shows that Argyle is a composite pipe formed by the coalescence of several steep-sided diatremes, each with their own feeder zones at depth, that were erupted along a NNE-trending fault. The ~1.2 Ga Argyle pipe is comprised of diamondiferous olivine lamproite volcaniclastic rocks and intruded by sparse olivine lamproite dykes. The volcaniclastic rocks are predominantly comprised of unconsolidated quartz-rich lapilli and coarse ash deposits formed by numerous phreatomagmatic eruptions of olivine lamproite magma through Mesoproterozoic water-rich sands and silts. Post-emplacement deformation has tilted the orebody 30° to the north and regional strike-slip faulting has offset, segmented, and elongated the orebody. Recent significant modifications of the geological model resulted from underground block cave operations, producing several critical lessons learnt. Diamond grade and quality reconciliation issues warranted a geological investigation which resulted in the recognition of new volcaniclastic olivine lamproite domains with a broad range of diamond grades, including some very high-grade units. The new lamproite domains had a significant effect on the block cave mining and resultant recovery of diamonds. The new findings enable a more coherent and detailed geological understanding of the volcanic emplacement and paragenetic sequence of the Argyle AK1 pipe. Structural modelling of the deposit also played a major role in the block cave mining tonnage recoveries and daily operations. The re-examination of the geology of the Argyle pipe and the results of this new information reinforces the need for ongoing robust geological work both in the early stages of mining a deposit and continued during the life of the mine.

Mar 22, 2022

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

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

Nov 29, 2022

Flue gases from electrical power station boilers, roasting, metallurgical and chemical plants could be treated by flotation using conventional flotation machines. The flue gases are introduced into the pulp instead of the air. The flotation media is a suspension of Ca(OH)2 or CaCO3 or a solution of NH4OH etc containing Na oleate as collector and frother. The SO2 and dust content of the initial flue gases were experimentally reduced by 100 to 1000 times in one flotation operation. The velocity of the flue gases through flotation machines could reach approximatively 0.4 to 0.5 m/s and more against 1.5 m/s reached in scrubber absorbers used for this purpose, but the quality of purification is expected to be better for flotation, which is essential for the cases of heavy polluted metallurgical and chemical flue gases. For some chemical plants the flue gases flotation media may be different and more suitable as compared to the above mentioned media. The proposed flotation method could be used for separation of dry grinded ores in the form of aerosols, with a realisation of flotation from a closed space (gas bubble in the pulp) onto the interface liquid-air where the particles are attached inside the bubbles.

Jan 1, 1993

By Hancock RG, Dewar GJA

The mining and exploration industry is governed both directly and indirectly by a complex and constantly changing regulatory and legal system, yet few technical professionals realise the extent to.which they are affected and that they are personally liable for any breaches. These breaches may result in criminal or civil prosecution that could involve significant financial penalties (to the extent that all personal assets are at risk) and even imprisonment. Generally, a professional at risk should be able to mount a due diligence defence in order to avoid or mitigate these consequences. Mineral property and company owners, directors, managers and employees are at risk, as are consultants, contractors and suppliers of equipment or consumables. Whilst all are liable for their personal decisions to act (or failure to act) in managing operations or carrying out directions, as well as for the actions of others under their control, the focus here will be on the exposure of the consultant. Consultants are usually driven by an internal desire to perform to a high standard because of personal pride in their work and concern for their professional reputation. However, there are an increasing number of external requirements for them to be able to demonstrate, if necessary, that their actions were based upon reasonable grounds and that their work conformed to current best practice standards. If they cannot do so, they may face potential personal Liability.

Jan 1, 1995

There are a number of methodologies which can be used for the preparation of environ- mental impact statements. Selection of a method depends upon the type of project and the environmental characteristics of the area where it is to be built. Most methods are satisfactory for assessing impacts on the physical environment but less so for the biological. Major problems may arise in deal ing with sociological issues because value judgements are involved. Several methods of approaching problems of this nature have been tried with some limited success.

Jan 1, 1976

By V Narayanaswamy

SustainabilityÆs imperative of economic development in tandem with social advancement and environmental protection is widely accepted, but much debate remains about the practical implications for the minerals processing technologies and practices for the future. Experience in other industry sectors however suggests that sustainability can be a value-adding framework for innovation in processing technologies, business models and management systems. This position paper explores how sustainability can drive innovation in minerals processing, by reviewing pertinent ideas and experiences gained in non-minerals sectors. Sustainable innovations can generally be broadly ranked from incremental to transformative, with each category having its own typical improvement potential, timescale and technological and operational challenges. This leads to a æmud mapÆ for sustainable innovation in minerals processing with three distinct tracks: eco-efficient operations; sustainable plant design and sustainable processing. Competing models for the sustainable innovation process through either forecasting or back-casting, have in common the strong reliance on vision, perspective and competency, which in turn highlights the importance of sustainability frameworks. Such sustainability frameworks provide normative goals and option elicitation prompts to assist with the analysis of current processes and scoping of more sustainable alternatives. A comparative analysis of five prominent environmental sustainability frameworks revealed three cross cutting sustainability themes that challenge current resource processing technologies and practices. These are: fate of materials (zero dissipation of materials); compatibility of materials and processes; and materials intensity of industrial products and processes. Although the sustainability concepts presented in this paper have not been extensively road tested in the minerals processing industry, there is ample evidence that recent initiatives in the Australian resource sector illustrate the applicability of the proposed framework. It is therefore argued that more in-depth assessment of sustainable innovation concepts would be a valuable contribution to the sustainable resource processing theory and practice.

Jan 1, 2004

By D Stephenson, N R. Steward

“TerraFlowingTM” is a dewatering process that addresses both the value proposition of Tailings as a Resource™, and the safe storage of tailings. “TerraFlowingTM” incorporates two stages of cyclone dewatering followed by centrifugation of the final dilute tailings stream. In this process three dewatered tailings streams are produced; a primary cyclone underflow, a secondary cyclone underflow and a centrifuge pulp. These three streams can be combined, or used, in various configurations to achieve different outcomes. The ability to vary the cyclone and centrifuge operations and configuration enables this process to deal with tailings feed variations in particle size distribution and mineralogy and deliver consistency, or design variations, in particle size distribution, tailings solids concentrations and recoveries. Water recovery can be up to 85% of the total water in the tailings with a stackable final tailings product achieved if the three tailings streams are combined in the maximum solids concentration configuration. The primary cyclone can be operated to deliver a particle size distribution suitable for tailings storage facility embankment construction or alternatives such as concrete structures or shotcrete for support. The secondary cyclone underflow and centrifuge pulp is suitable for beaching deposition within the tailings storage facility.

Jul 1, 2021

By Giannini L. M

The determination of the "optimum pit limit" of a mine has long been considered as a fundamental problem of mine planning. A number of mathematical techniques have been proposed to solve this problem some of the more elaborate ones posing considerable computational difficulties for their implementation. Barnes and Johnson recently introduced "bounding techniques" to ease the computational effort required for determining the optimum pit. The aim of this paper is to point out and correct some errors in their techniques. A presentation of a general bounding algorithm is given.

Jan 1, 1985

By U JSger

The Westerschelde tunnel will be the first permanent road link between the Dutch regions of South Beveland and South Flanders. Two tunnel tubes, each 6.6 km long, will be driven using the shield tunnelling method. The difficult ground conditions and a water pressure of up to 6.5 bar make great demands on the design. This paper describes the problems and their solutions.

Jan 1, 1999

By D Hope, D Mitchell, B Metcalfe

In recent years there has been a major change among mining companies in their mining methods. This has been driven by the need to increase shareholder value and optimising the value from an operation. With this understanding there has been a need for all producers to become more efficient in their mining processes. An analysis of the coal losses at Mount Thorley Operations indicated that the major losses were in the dragline section of the mine due to coal damage from throw blasting. This damage was evident after the removal of the overburden by the dragline.Coal and Allied Mount Thorley Mine in partnership with Orica Explosives developed a process to reduce the coal loss associated with the throw blasting of Mt Thorley. Orica provided its specialised knowledge and experience in the drilling and blasting area and combined this with the local mining knowledge and expertise of Mount Thorley Operations personnel to conduct the project. This partnership reduced coal loss in excess of 50 per cent whilst maintaining targeted dragline productivity.

Jan 1, 2001