Search Documents

This paper describes an investigation of the sampling problems which contributed to erroneous Concentrator production forecasts at the mining operation of Bougainville Copper Ltd (BCL) in the North Solomons province of Papua/New Guinea.Reference figures provided by independently verified commercial shipment data demonstrated the existence of a bias in the calculated Concentrator production; the challenge was to identify systematic errors in each of the contributory measurements (feed tonnage and feed, tailings and concentrate grades).The uncertainty surrounding specific sampling and measurement errors precluded optimum metallurgical control and performance of the milling circuit, encouraged disputes about the difference between Mine versus Concentrator production estimates, and cast some doubt on efforts to follow political guidelines concerning a maximum feed tonnage or recovery oriented mill operating concept.An evaluation of routine results as well as specifically targeted test work identified the sampling errors associated with measured individual parameters.The emphasis in this report is on the procedure for quantitative error assessments.The measured performance of a mineral dressing plant is subject to a systematic error balance which can be derived from the more familiar weight and metal balances such as the two- or three-product formula.The resulting equations are generally valid, and they are applied to the measurements obtained at BCL's Concentrator to illustrate the method.

Jan 1, 1976

By A Lim

"As Abel Mine continues to expand and increase production, the requirements of the ventilationsystem have also increased. This paper will outline the stages undertaken to increase the AbelMine ventilation system from an operating position of 110 m3/s and 500 Pa to the current operating position of 220 m3/s and 1.6 kPa and outline steps to be taken to ensure all future requirements will be able to be ventilated."

Jun 1, 2012

As a number of underground fires have unfortunately happened in the Broken Hill mining district, the writer trusts that a paper dealing with such a subject may prove of interest. To simplify matters, the subject is classed under three mainheadings- I Origin of fires; II Methods of subduing them; III Precautions to minimize the risk of their occurrence.Underground fires may be started in three ways - arson, spontaneous combustion, or carelessness.With regard to the first-mentioned cause, direct evidence is usually lacking to prove that any fire has been caused maliciously; Though definite proof of spontaneous combustion having been the cause of a mine fire has not been brought forward, nevertheless it should be considered, especially in the case of sulphide ore bodies of a more or less friable nature. The writer has been informed on reliable authority that in an open stope on the...

Jan 1, 1911

By L Crew, S Jackson

A trial of an Adept Online Ore Sizer (OOS) was undertaken at the WMC Leinster Nickel Operation (LNO) in the first half of 2000. During this time the On Line Ore Sizer has been shown to be a robust and accurate instrument for measuring mill feed ore size. Data collected during the trial indicates significant variation in the F80 of the SAG mill feed. The effects of feed size on milling parameters such as mill weight, mill power draw and mill efficiency appears to be dependent on the ore blend treated. With some ore blends a weak positive correlation was found between ore size and mill weight and milling efficiency but with others no correlation is evident. It is believed that the OOS will become a vital piece of equipment in the future as LNO continues to optimises its milling circuit.

Jan 1, 2000

Technological advances evolve in different ways; many are the result of years of application of scientific method. i.e. Observation Deduction Hypothesis Proof In the mining industry, better explosives, drill bits or reagents are likely to evolve in this way. The scientific method is suited to the application of conventional management structures. Other advances are simply the result of a "brainstorm", or building a better mousetrap. Such inspiration probably resulted in "Split Set" rock bolts, or the first use of a vacuum cleaner principle for shaft mucking. Individual consultants can apply lateral thinking to generate such inspiration. In gathering material for the presentation of this paper, I sent a.letter to all members of the Mineral Industry Consultants Association asking them to nominate problems in the industry requiring investigation. The answers have been divided into two classifications - contract research underway and identified problems requiring solutions.

Jan 1, 1986

By Watson D. F

Armstrong's (1983) criticisms of PhiIip and Watson's (1982b) note on optimal drilling patterns are based on misinterpretation, supported by errors in geometry. Furthermore, Armstrong argues conceptually from the perspective of Matheronian geostatistics, as does also Rudenno (1983a, b). Thus, both authors embrace a global, probabiIistic method of assessing spatial data sets, an approach that must be contrasted strongly with local, deterministic interpolation methods. Some of the important assumptions of geostatistics are outlined and the non-unique nature of the method discussed. A probabilistic approach can be judged appropriate when exploration data are erratic, or known to be unreliable, or when extrapolation is desired. Where data are treated as exact, kriging can give the most biased result if tested against other interpolation methods. We reiterate our previous conclusion that the equilateral triangular grid is approximately 30 per cent more efficient (in terms of numbers of drill holes) compared with a square grid for the same maximum interpolation distance. This is simply due to the improved isotropy of sampling. New, locally-based, deterministic methods for computing ore reserves seem to be required.

Jan 1, 1984

The beneficiation of heavy metal oxides, such as iron ore, is usually performed with heavy medium separation in cyclones, static baths and lately with Larcodems. Atomized ferrosilicon is most suitable as a heavy medium at densities above 3600 kg/m3 whereas a mixture of milled and atomized ferrosilicon is suitable at densities below 3600 kg/m3. When operating a beneficiation plant at densities higher than 3600 kg/m3 the quality of the ferrosilicon particles is an important factor that influences the control of the beneficiation process. Therefore, it is important to know how the rheology would be affected by the ferrosilicon quality as it also influences the control of the process at these elevated densities.

Jan 1, 2002

By Armstrong M

Two methods of Monte-Carlo simulations, one suggested by Matheron (1972) and the other by Rudenno (1983), have been tested for simulating coal deposits. To do this 2160 values of ash percentages were simulated using 60 known data points in a two dimensional grid, 20 m x 40 m. 1L is found that while both methods conserve the mean of the known distribution in the results of the simulations, only the first method reproduces the spatial covariance (i.e. the variogram), of the experimental data. The results show that for simulation of regionalized variables only the first method tested yields the desired results.

Jan 1, 1985

The subject of government involvement in industry is, to say the least, a touchy one. For many it conjures up thoughts of socialisation or nationalisation. For others it is a desirable objective and is seen as a means of social reform by giving government a greater say in the control and distribution of human, financial and natural resources for the betterment of the community. Whatever your point of view, it is difficult to deny that government involvement exists to lesser or greater degrees in all industries. The mining industry is no exception and the degree of government involvement is probably greater than it is in other industries. I think it is important to remember when talking about government involvement in industry to recognise that there are different types of involvement and that all governments have a right, if they so desire, to become involved in whatever way they choose. The decision of a government to increase its direct or indirect involvement must, of course, be taken in the national interest. Governments, if we are still old fashioned enough to believe in ministerial and electoral responsibility, must make up their own minds about whether their actions are in the national interest and they must be prepared to accept the consequences of that action, good or bad. For instance, they must decide

Jan 1, 1975

The efficient development and exploitation of an orebody relies on an understanding of the mineral characteristics of the deposit. This information is valuable throughout the mining cycle - during exploration, assessment, testing, design, operation and rehabilitation. Problems can arise at each stage if there is an inadequate appreciation of the mineralogy involved and its effects on the treatment process. Modern image analysis systems now permit a more quantitative understanding of the mineralogy of an ore to be gathered. Where previously the metallurgist had to rely on qualitative information to guide technical decisions, it is now possible to give numerical estimates to the compositional and textural properties which govern the mineral concentration processes. Ore samples can be characterised according to modal abundances, mineral grain size parameters and mineral associations, all of which affect the liberation and concentration of the values. The paper will discuss the application of quantitative process mineralogy by considering a number of case studies. These include: ore characterisation to assist in exploration, assessment and mine planning; modal analysis of complex mineral suites to assist in the evaluation of ores, the deportment of values between products and the recovery or loss of these values; liberation analysis for ore testing, plant optimisation and performance monitoring; and characterisation of tailing to guide estimates of leachability, stability and rehabilitation options.

Jan 1, 1998

The Kundana underground narrow vein gold mine had a recent history of large and damaging seismic events. Following a period of seismic events on 30 July 2001, in which nine miners were temporarily entrapped at depth due to falls of ground in several parts of the decline, the mine operation was required to develop a seismic management system to mitigate seismic risk to the operation. A micro seismic systems and boundary element modelling of mine sequence highlighted large-scale footwall faults and the mining of gold bearing shear veins to be focal structures for seismic energy release between depths of 300 m to the base of mining at 650 m. The integration of seismic data, identification of geological structures and mapping of zones of failed rockmass led to the successful generation of a non linear boundary element model and a seismic hazard strategy. This enabled mine sequences to be assessed daily, monthly and periodically for potential seismic hazards and therefore assigned both economic and personnel risks for the recovery of the ore reserve at the Kundana Underground Operation.

Jan 1, 2005

By James D

Fletcher Challenge Limited through its subsidiary Grampian Mining Co Ltd has carried out an ore evaluation of one of New Zealand's largest known deposits of ilmenite located at Barrytown on the west coast of the -South Island, New Zealand.The ilmenite is located in a beach sand environment which has previously been mined for gold. Two analytical techniques were developed to quantify the resource. Considerable difficulty was experienced in this phase of the evaluation due to the presence of major inclusions within the ilmenite grains. Wet and dry concentration circuits, utilizing spiral, wet magnet, high tension and plate electrostatic separators have been G47designed to produce ilmenite from the ore. Studies to utilize the titanium content of the Barrytown ilmenite have been made. Recent work has been directed towards a titanium dioxide pigment process.

Jan 1, 1986

Despite mineral sand occurrences having been noted since the 1970s, the Wemen North Mine is the first operation to commence commercial mining within the inland Murray Basin. The deposit was discovered in the 1990s and, following lengthy resource development, mining commenced in 2001. This initial mine was established as a pilot operation to test the commercial viability of mining in the Murray Basin, with subsequent expansions planned if the mine proves successful. The deposit lies beneath arable farmland close to the Murray River and is hosted by Pliocene marine sands, with a geometry resembling a classical beach strand placer. The operation utilises traditional dry mining overburden removal techniques, with ore mining carried out using a floating dredge and concentrator. This paper looks at the geology of the Wemen North deposit, the mining techniques and challenges as well as grade control practices employed to mine this palaeo-beach placer deposit.

Jan 1, 2003

By D J. Clark, S Hewson, T Li

Cadia Hill Pit is a gold copper porphyry deposit hosted in monzonite. The pit slope design is primarily based on structural controls related to faults and shears with largely massive rock masses between the structures. The slope design attempts to achieve an optimum configuration at a bench to overall scale, considering economics and safety implications against the geotechnical and structural conditions. To date the slopes have been mined at interramp angles of up to 60¦ over heights of 120 m. Limited slope and batter failures that have occurred are structurally controlled and occur rapidly. The pit-mining schedule requires concurrent mining of part of the final pit walls and the progressive interim cutbacks. Engineering and operational solutions to hazard reduction and risk management issues have been implemented wherever viable to æengineerÆ out the hazard and mitigate the risks. However, comprehensive management plans and operating procedures have also played a vital role. This paper details the management plan and the operating procedures that have been developed and implemented to mitigate the risks associated with rock falls.

Jan 1, 2003

By Moore R

An intensive safety campaign at Mount Isa Mines Limited from 1956 to 1966 saw the lost time accident frequency rate fall to half its original level. A review of the safety programme was carried out in 1967 and in 1968 the Five Point Safety System was introduced. The seven years since its introduction have been years of significant achievement both in production and safety. Improving safety is a fundamental part of Mount Isa Mines Limited's policy and this system has been a major tool in implementing that policy. To be successful personnel need to be prepared and trained for its introduction and subsequently counselled on its use. A carefully prepared programme is required to phase in various aspects of the system and to make use of complementary steps. The system has been a success and it is anticipated that the continued drive to improve the use of principles of the system will further improve safety. It is hoped that this paper will be of value to those personnel concerned with industrial safety in Australia.

Jan 1, 1975

By Torrance AC

A joint research programme conducted by BHP Central Research Laboratories and Du Pont Wesfarmers Pty Ltd examined the effect of the size of cast primers on the run up and steady state detonation veloci- ties of ammonium nitrate based explosives as a function of blasthole diameter. Both continuous and point to point velocity of detonation meas- urement techniques were used. The field trials examined a number of the Du Pont HDP series of primers in conjunction with ANFO, emulsion and watergel explosives. Results indicate that the run up velocity of 187mm diameter ANFO charges is negligible using cast primers as small as 150g. owever, emulsion and watergel explosives did exhibit run up in both 187 and 311mm diameter blastholes, independent of the size of primer. This could last from 7 to 10 blasthole diameters.

Jan 1, 1988

The prime requirement is market, which for NZ inevitably means overseas markets. In order to be internationally competitive, the economies of scale and mechanical handling are essential. Since significant markets have not been sought, the full extent of our industrial mineral potential is not known. In general the technology exists to impart the desired quality, but at a price. Price is the main constraint, which may confine truly competitive operations to coastal situations to avoid high internal freight charges. Some commercial deposits of construction materials are being sterilised by zoning, making the costs to the consumer and country unnecessarily high. Unless management is enlightened and marketing is forceful, it can restrict growth. There is a good case to mount a search for phosphate minerals. The main growth areas are likely to be direct shipping ores like limestone, silica sand, and olivine, but in particular pumice.

Jan 1, 1978

The treatment of beach sands in'' the Bunbury/Capel' area for the extraction of ilmenite is a very recent development in the mining industry in'J7estern Australia. Nevertheless since the commencement of production in 1956, ilmenite has become the sixth most important mineral produced. The increasing world recognition of W.A. as a major' Iiroducer of ilmenite is due primarily ' to its low chromic oxide. ; (Cr203 content,, 0,03% to 0.04%, combined with a medium to high grade TiO2 content, 54% - 6 , supported by large reserves, a'. stable government with close access to good shipping facilities.. Ilmenite is produced from-these deposits at low-costs, enabling the industry to compete on world markets despite high rates for sea freights because of the distance from.major markets.

Jan 1, 1964

In engineering applications of explosives for rock breaking, the released energy is expended mainly into heat, rock crushing and fracturing, seismic waves, air blast, and noise. Those parts of energy which pass into seismic waves and air wave create environmental problems since they are transmitted away from the blast site. In order to predict the environmental effects accurately, one must be able to predict the energy distribution at the source. The energy distribution at the source is significantly controlled by the blast constriction. Consequently, the accuracy of prediction and control of ground vibrations generated by blasting is affected by various matrices of blasting constriction.

Jan 1, 1986

By Finch JA, Uribe-Salas A

The relationship between the process variables and hydrodynamics of a downflow concurrent column (Jameson cell) was investigated in both two and three-phase systems. Gas holdups from 10 to -60 per cent were obtained at gas rates up to 15 cm/s (STP), liquid (slurry) rates up to 25 cm/s, frother concentrations of 5 and 25 ppm, and slurry density (silica) up to 1.23 g/cm3 ina 3.8 cm diameter, 190 cm high column with a 0.5 cm diameter nozzle. Gas holdup decreases with feed rate and increases with gas rate, reaching a maximum (-60 per cent) at a gas rate to feed rate ratio of about one. Gas holdups were higher with slurry compared to water as feed. Stable operation was difficult to maintain at high gas rates especially with low frother dosage; operation was not possible without some frother. Instability was characterised by loss of pool level or formation of slugs. The slugs could move up or down or remain oscillatory. A quantitative relationship between the variables and gas holdup or onset of instability was not identified. Conductivity and pressure-based techniques were successfully tested on-line for estimation of gas holdup and to judge the state of operation (eg formation of slugs).

Jan 1, 1993