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By Barria J, Mencho J, Gonzalez GD

An extended Kalman Filter is used to build an on-line estimator of total ore, fine ore and water hold-ups in a SAG mill. In addition, an equivalent grinding rate from coarse to fine ore, as well as the discharge rates of solids (fines) and water are also estimated as part of the adaptation procedure of the model used for the Kalman Filter. The measurements used in the Kalman Filter estimator are the total mill weight provided by load cells, and inferred discharge flows of fines and water from flow and density measurements performed downstream. The net ore and water feed to the SAG mill are used as inputs to the estimator, and also the proportion of fine ore in the feed. As an example of how to introduce robustness in the estimation in the face of sensor bias errors, an estimation of the load cell bias error is introduced in the estimator, thus providing self calibration. The estimator presented in this paper has been tested by simulation using a detailed SAG mill mechanistic dynamic model comprising 27 size fractions well fitted to a pilot mill. The maximum error in the estimation of the operational variables - total and fine ore as well as the mill contents under different operating conditions - is about ten per cent.

Jan 1, 1993

By P N. Holtham

Magnetic separation is routinely used in the processing of titanium minerals, and the efficiency of these operations can be determined by measuring the magnetic properties of the process streams. The valuable components in the feed to a titanium minerals plant have specific magnetic susceptibilities ranging from -10-9 m3 kg-1 (zircon) to 10-6 m3 kg-1 (ilmenite). However, in an industrial environment, in which the mineral temperature may range from 20 to 120¦C, it is difficult to measure susceptibilities lower than about 10-7 m3 kg-1. Hence laboratory testing of spot samples from magnetic separators is currently required to obtain accurate performance data. This is an inherently slow process and where feed grades are variable, optimum performance of magnetic separators is generally not achieved. This paper describes the development of an inductance-based instrument for measuring very low levels of magnetic susceptibility on-line. The signal from the instrument can be used for process control purposes to maintain optimum magnetic separator performance. A prototype instrument has been installed in the zircon scavenger circuit in an Australian titanium minerals plant. The circuit consists of a roll magnetic separator treating a feed consisting mainly of monazite and stained zircon. The monazite-rich magnetic fraction is returned to the mine site for disposal, while the non-magnetic fraction is recycled to the zircon wet circuit. Splitter positions in the separator are adjusted when the final zircon product fails to meet specification, or the magnetic fraction contains more than 30 per cent zircon. Weekly composite grain counts show that sub-optimal operation of the magnetic separator results in significant zircon losses into the magnetics fraction. Using the instrument, the zircon content of this stream can now be accurately determined from the measured magnetic susceptibility, provided a correction for the effect of mineral temperature is applied using the Curie - Weiss relationship.

Jan 1, 2001

By P N. Holtham

Magnetic separation is routinely used in the processing of titaniumminerals, and the efficiency of these operations can be determined bymeasuring the magnetic properties of the process streams. The valuable components in the feed to a titanium minerals plant have specific magnetic susceptibilities ranging from -10-9 m3 kg-1 (zircon) to 10-6 m3 kg-1 (ilmenite). However, in an industrial environment, in which the mineral temperature may range from 20 to 120¦C, it is difficult to measure susceptibilities lower than about 10-7 m3 kg-1. Hence laboratory testing of spot samples from magnetic separators is currently required to obtain accurate performance data. This is an inherently slow process and where feed grades are variable, optimum performance of magnetic separators is generally not achieved.This paper describes the development of an inductance-basedinstrument for measuring very low levels of magnetic susceptibilityon-line. The signal from the instrument can be used for process control purposes to maintain optimum magnetic separator performance.A prototype instrument has been installed in the zircon scavengercircuit in an Australian titanium minerals plant. The circuit consists of a roll magnetic separator treating a feed consisting mainly of monazite and stained zircon. The monazite-rich magnetic fraction is returned to the mine site for disposal, while the non-magnetic fraction is recycled to the zircon wet circuit. Splitter positions in the separator are adjusted when the final zircon product fails to meet specification, or the magnetic fraction contains more than 30 per cent zircon. Weekly composite grain counts show that sub-optimal operation of the magnetic separator results in significant zircon losses into the magnetics fraction.Using the instrument, the zircon content of this stream can now beaccurately determined from the measured magnetic susceptibility,provided a correction for the effect of mineral temperature is applied using the Curie - Weiss relationship.

Jan 1, 2001

By P Barrette

The manual gravimetric drying moisture determination methods currently employed by most mineral processing plants fail to provide timely and accurate information required for automatic control. The costs associated with transporting and handling concentrates represent a major portion of the overall treatment price. When considering the cash flow of a mining operation that is governed by both the smelter contract, with moisture penalties and the quantity and quality of the concentrates shipped, any tool that provides real-time feedback on the process is vital (Edwards, RP 1994). The introduction of an on-line moisture sensor would become a welcome addition to the process control field instrumentation package now applied. A novel on-line determination system for ore concentrate moisture content would replace the tedious manual procedure. Since the introduction of microelectronic-based control systems, operators have strived to reduce the treatment costs to the minimum. Therefore a representative and timely determination of on-line moisture content becomes vital for control set points and timely feedback. Reliable sensors have long been on the æwish listÆ of mineral processors since the problem has always been that you can only control what you can measure, (Konigsmann, 1990). Today, the task of moisture determination is still done by the classical technique of loss in weight utilising uncontrolled procedures. These same methods were introduced in the earliest base metal concentrators. Generally, it is acceptable to have ore concentrate moisture content vary within a range of seven to nine percent, but controlling the moisture content below eight percent is a difficult task with a manually controlled system. Many times, delays in manually achieving reliable feedback of the moisture content results in the moisture varying from five to twelve percent before corrective actions can be made. This paper first reviews the traditional and widely available methods for determining moisture content in granular materials by applying physical principals and properties to measure moisture content. All methods are in some form affected when employed on mineral ore concentrates. This paper introduces and describes a unique and promising novel on-line moisture sensor employed for mineral processing de-watering applications, which not only automates the tedious tasks but also results in reliable moisture feedback that can be used in the optimisation of the de-watering process equipment such as pressure or vacuum filters and fuel-fired driers. Finally, two measurement applications will be presented to indicate the usefulness and to summarise the measurement requirements for the proposed method of employing drag force and mechanical properties of the material itself to determine the moisture content. The commercial model of the equipment is described with the features and benefits to the users summarised.

Jan 1, 2003

By Millen M. J, Rainey S, Sowerby B. D

The control of size reduction in grinding machines and circuits may be enhanced by a continuous and accurate measurement of the particle size of solids in appropriate process streams. This paper presents a brief review of commercial particle s

Jan 1, 1997

By K Heiskanen, R A. Grau

Gas velocity (Jg) measurements conducted close to the froth-pulp interface over the cross-section of a flotation cell reveal how efficiently the incoming air is being dispersed throughout the volume of the cell. Furthermore, measurements of Jg at deepest locations in the cell provide valuable information about air recirculation and dispersion conditions in the bulk volume of the cell. Gas velocity in flotation cells has predominantly been measured by a transient capture of gas in a graduated probe. In this project, a new sensor for measuring gas velocity in an on-line manner was developed. A probe is partially immersed in the flotation machine, below the froth-liquid interface. The probe is used to collect the rising air bubbles from the liquid phase. The liquid-froth interface is shifted into the probe under vacuum. A controlled vacuum is kept inside the probe. As air bubbles burst inside the probe, the excess of air is continuously removed from the probe via suction. The removed air is measured using a mass flow meter. The fully automated sensor allows us to continuously measure Jg at different location in a flotation machine. An experimental programme was carried out in a 10 cm diameter laboratory flotation column to determine the accuracy and repeatability of the automated sensor. The new sensor was used for evaluating gas dispersion conditions in a 215 litre transparent laboratory scale flotation cell. Gas velocity distributions along the radial and axial directions of the cell were measured over a wide range of operating conditions. The operating conditions in the cell were modified by altering impeller speed and air flow rate. Two different rotor-stator mechanisms were utilised to disperse the air in the cell, the MultiMix and the FreeFlow mechanism. In this paper, a description of the gas velocity sensor is given, and the results of the experimental work are discussed in detail.

Jan 1, 2005

By D Morgan, K Jones

"In March 2015 Northparkes Mines (NPM) installed a process mineralogy facility on-site. The laboratory included a TESCAN TIMA scanning electron microscope (SEM) and was the first SEM facility to be commissioned on a mine site in Australia. While the initial intent of the quantitative mineralogy laboratory was to provide information to drive processing plant improvements, in practice, it has been utilised for so much more and is now serving as an integral link between departments on-site. This multidisciplinary approach to orebody knowledge is a new strategy for NPM whereby all parts of the value chain are aligned towards the common goal of achieving process efficiency and stability while still maintaining high throughputs. The NPM experience is presented as a case study to illustrate how on-site process mineralogy can drive a realignment in business strategy with a common goal of mill optimisation, stability and more realistic forecasting through orebody knowledge and information sharing between disciplines.Citation:Jones, K and Morgan, D, 2016. On-site Process Mineralogy - Linking Departments and Disciplines with the Common Goal of Increasing Plant Performance, in Proceedings 13th AusIMM Mill Operators’ Conference 2016, pp 149–156 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Oct 10, 2016

There are many variables in a flotation concentrator, some of which are outside the actual flotation stage, which affect metallurgical performance. The number of such variables which can now be measured on a continuous basis has increased significantly over the past 20 years. They can be broadly classified under the headings of physical, chemical, and elemental. In this paper reference is made to a number of such variables, and comment is made on the state of the art in their measurement. Although not confined to development in Australia, particular reference is made to the considerable Australian contribution in this area of Technology.

Jan 1, 1984

By Mathew P. J

The CSIRO Division of Mineral and Process Engineering in Melbourne has been developing on-stream analysis sensors based on neutron and gamma radiation for better control of quality and process operations. This has resulted in the development of Ironscan, an on-stream analyser that measures the iron content of both lump and fine iron ore on conveyor belts. It can be mounted under existing conveyors with minimal modifications to the conveyor structure and can cope with steel cables in the belt. An interface gauge and an on-stream coal ash analyser have also been developed, both based on measurement of natural radioactivity. The interface gauge monitors the interface between liquor and mud in thickeners and washers, provided the natural radioactivity of the mud is sufficiently high to detect it above background. The natural-gamma ash gauge is a valuable addition to the Coalscan range of ash gauges. It is applicable to heavily laden coal conveyors or bins where the coal bed thickness exceeds 30 cm, and also to lightly laden conveyors, provided the coal is profiled on the conveyor.

Jan 1, 1991

The lead concentration of flotation feed ore slurries is determined using two ?-ray absorption gauges mounted directly on a 6 in. diameter flotation feed pipeline. One gauge is a conventional "density" gauge using CS137. The other is a "lead-sensitive" gauge, which depends on the preferential absorption. by lead of 225 key y-rays resulting from Compton backscatter of CS137 y-rays.Gauge outputs are combined using an analogue computer the output signal of which is directly proportional to the lead concentration of the pulp. The accuracy of measurement of the pulp lead concentration is ± 3·6 per cent for ore slurries with lead concentrations in the range 0'07-0·16 g/c.c. and pulp densities 1.43-1.60 g/c.c.This paper sets out the development of the technique and details are given of the two experiments (1964, 1966) conducted in the plant at North Broken Hill Limited. The installation of the two-gauge system inthe plant during May 1968 is described. Details are given of the calibration technique used and the results obtained.

Jan 1, 1969

An on-stream iron ore analyser has been developed in collaborationwith Hamersley Iron Pty. Limited for determining the iron content ofboth lump (- 30+ 6 mm particle size) and fines ( - 6 mm particle size)on conveyor belts. The analyser, which is called IRONSCAN, is basedon pair production, and is now commercially available from Mineral ControllnstrumentationLimited (MC!) in Adelaide. It can be mounted underexisting conveyor belts with minimal modifications to the conveyor structure,and the presence of steel cables in the belt does not interfere oncethe analyser has been correctly calibrated. The analyser has been extensivelytested on both lump and fines on the shiploading conveyor at Dampier,and typically the root mean square (Lm.s.) deviation between singleIRONSCAN measurements and conventional chemical analyses is betterthan 0.5070 Fe. It is currently being evaluated on - 150 mm ore from theprimary crusher at Mount Tom Price, and initial result are encouraging.The principal advantage of IRONSCAN is that it provides rapid informationon ore grades. But perhaps its greatest potential is at the primarycrusher where conventional sampling and analysis is very expensive toimplement.

Jan 1, 1988

In response to requests from the iron ore mining industry, the Commonwealth Scientific and Industrial Research Organisation (CSIRO) Division of Mineral Physics has developed a number of bulk analysis techniques in which analyses are obtained directly from ore samples weighing many kilograms or from ore located on conveyor belts.Because penetrating neutron and gamma radiation is used, measurements are obtained from a large volume of ore, which ensures thal the analyses are represelllative of the bulk.Two different gamma-ray techniques have been developed to measure iron ore grade. The first is based on backscallering of 60CO gamma rays, while the second involves measurement of the annihilation radiation which arises when the ore is irradiated wilh 226Ra gamma rays. Both techniques measure the iron concentration with an accuracy (1 s) of better than 0.4% Fe.A thermal-neutron irradiation technique using a 252Cf neutron source has been developed for the simultaneous determination of iron and the aluminium impurity (expressed as AI2O3) in iron ore fines on a conveyor bell. Because the conveyor speed must not exceed about 0.05 m/s, if good accuracy for AI2O3 is required, an auxiliary analysis bell is required Lo avoid inLerference with normal ore processing. Dynamic trials have demonstrated that accuracies of 0.6% Fe and 0.1% AI2O3 can be obtained.

Jan 1, 1985

By Holmes R. J, Miles J. G

An on-stream shale detector has been developed that is suitable for use on conveyor belts carrying iron ore of up to 200 mm particle size. The shale is distinguished from high-grade iron ore by means of the substantially greater total natural gamma-ray activity (400-3000 keV) of the shale, which is due to the presence of uranium (214Bi), thorium (208TI) and potassium (40K). Other gangue materials, sueh as highly siliceous cherts and jaspilites, escape detection because of their low activity. A dynamic trial of the shale detector at Mt Whaleback, using a large-volume (100 × 100 400 mm long) "Polyscin" Nal(TI) gamma-ray detector, demonstrated that as little as 20 tonne of ore on a conveyor belt (equivalent to partial truckloads of ore) can readily be monitored for shale content.

Jan 1, 1981

Copper heap leaching involves both the simultaneous and sequential leaching of very large tonnages of ore over long periods of time. It is not unusual to be leaching three or four million tonnes over periods of 12 to 18 months. As a consequenc

Jan 1, 1998

By I Özen, G Chitumbura

A paper identifying anticipated challenges in the extraction of the N3500 Orebody at Glencore Xstrata Copper’s Mount Isa Copper Operations was written in 2007. The paper identified the depth of the deposit, the anticipated high stresses, talc alteration and issues with ground support as factors that may affect production. A number of strategies were planned to cope with these issues. After six years of extraction those strategies are evaluated and additional measures taken are outlined. Strategies to cope with the limited mine life are presented, and methods to overcome additional challenges encountered during production are described.CITATION:Chitumbura, G, Matthews, D, Özen, I and Jackson, S, 2014. One mile underground – mining the N3500 orebody at Mount Isa Mines, in Proceedings 12th AusIMM Underground Operators’ Conference 2014 , pp 265–282 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Mar 24, 2014

Production sharing and cost apportionment in joint ventures is commonplace in Australasia today and elsewhere. It is a recognised convention that, with the exception of a free carry situation, joint venture participants usually share the proceeds of the joint venture in direct proportion to their respective participating interest, after having first paid its respective cash calls, in advance, to cover the projectÆs ongoing operating and capital cost requirements.In surface mines, the parties simply pay their way and take their proceeds in this manner. In underground mines, the situation is no different, though treatment of capital, depreciation and tax may differ between the parties. A common feature in many cases is the creation of a joint venture entity to conduct the business. This entity then collects cash from the parties, banks it, employs the staff, runs the operation, provides reports and pays out the proceeds. This convention appears to be relatively simple in application. In practice, it has been known to be complicated in the situation where the participants take their product at the mine gate and undertake their own marketing and selling arrangements. A more complex situation presents itself where the joint venture tenement boundary with an unrelated third party straddles an economic deposit. In this scenario, both the joint venture parties and the third party may wish to mine the deposit, sharing some infrastructure and costs, yet taking their own product as it is produced. A case study outlining such a situation is presented in the paper, outlining firstly how the major cost categories were identified and treated for cost apportionment purposes. Secondly, a mechanism for the equitable apportionment of product is suggested. Finally, issues such as timing and cost reporting are dealt with, together with a checklist of points which should be considered when a similar situation might arise in the future.

Jan 1, 2002

By G A. Wellwood

What do all iron ore mines have in common? Perfect production days! Yes, those harmonious 24-hour periods when the stars align and the daily output number rockets past the long-term average to hit new heights. While perfect days are always welcome, the focusing question iswas that just a ‘flash in the pan’ (due to a special cause) or an indication of the process’s capability (with clues to the common causes) which, if addressed, could make every day perfect? In the context of today’s operating environment, with the need to maximise productivity at minimum cost, it’s an important question.Investigations reveal that the throughput difference between a perfect production day and the average is often in the order of 40 per cent, and that bulk solids handling (BSH) system deficiencies are the largest (>50 per cent) class of lost opportunity. Root causes for underperformance of elements in BSH systems can often be traced back to the detailed design and even study-stage oversights. Essentially baked into the fabricated plant, operations are effectively forced to accept them at the point of practical completion and then deal with the consequences for the life of the mine. Subsequent normalisation of these defects in the planning process reduces visibility and hence the impetus for long-term solutions in favour of lower targets and quick fixes to keep the show on the road. On an industry wide basis the design processes and assumptions responsible for BSH system underperformance become enshrined as common practice and hence repeated across sites and organisations.In addition to making the case for action, practical steps that can be taken to help realise the significant productivity prize and avoid the problems in first place are provided.CITATION:Wellwood, G A, 2017. One perfect (production) day – a bulk solids handling perspective, in Proceedings Iron Ore 2017, pp 443–452 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 24, 2017

By Marwick PL

As part of its operations Hamersley Iron operates a heavy medium Concentrator to upgrade low grade, unsaleable iron ore to produce saleable lump and fines products. Firstly, the attempts at delivering a blended feed in both chemical and physical characteristics are presented. Improvements in blending controls are shown to have given process performance improvements. Secondly, improvements to the feed preparation section are detailed. These alterations are providing a much cleaner feed to the subsequent processing stages.

Jan 1, 1987

By Mining Geophysics

Modern geostatistics has eliminated much of the guess-work in ore reserve estimation, and can calculate levels of confidence for the reserve estimate. Geological modelling software has brought about a revolution in the communication of complex geo-variables to mining engineers, metallurgists, surveyors and managers. Mine planning and scheduling can now avail itself of a veritable toolbox of enabling technologies.

Jan 1, 1994

By I J. Holland

Located in North West Queensland, XstrataÆs Mount Isa Copper Operations (MICO) is one of the largest underground mines in Australia with annual production exceeding six million tonnes of ore with average copper grades of three per cent. As at 30 June 2006, the Ore Reserve inventory totalled 87 Mt, with annual diamond drilling planned at >40 000 m in order to convert existing resources and test and define exploration targets. The role of the geology department within MICO is to collect, interpret and communicate relevant geological information to ensure the optimal extraction of ore. Routine underground inspections across multiple ore sources are undertaken and the information derived is then distributed to a range of professionals, operational personnel and management. The information is a æreal-timeÆ geological view for the stakeholders. Ongoing data collection and interpretation has developed a strong geological input to all mine planning processes within MICO. This has created strong synergies between mine planning professionals and a throughput benefit has been seen all the way to the concentrator. The MICO geological framework also provides avenues for a geological focus away from short-term production requirements, and as a result significant orebody scale observations and patterns have been realised that have led to an increase in the accuracy of geological and resource models. This has provided practical benefits for short-term scheduling and production, whilst enabling the realisation of long-term benefits that have a strong potential to increase the volume and value of the MICO resource. This paper will discuss the various mine geology contributions at MICO and illustrate some examples where mine geological input from graduate level has added significant value to the MICO business.

Jan 1, 2007