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By T Baumgartl, C Gonzales, A Soliman, M Edraki

A soil cover isolates potentially acid-forming (PAF) mine wastes from atmospheric interaction and thereby mitigates acid mine drainage. As a cover that comprises either a single layer or a composite barrier, it essentially manages percolating rain water from flowing into these PAF materials and minimises air flow as oxygen has low diffusivity in saturated soils. However, the availability of suitable soils as cover materials is limited, especially in arid and semi-arid regions where weathering rates are low.This paper investigates the potential use of mine wastes as cover materials in a water-shedding soil cover in north-west Queensland. Four cover trial plots were built using mine wastes as cover materials. Each 2.3 m cover trial plot consisted of a 1.5 m soil cover made up of waste rocks and fines, a 0.5 m drainage layer that consisted of 0.1 m waste rock aggregates and a base layer made up of blended mine tailings. The hydrologic properties of cover materials were determined by in situ measurements and laboratory experiments, which, in turn, were used as input in a numerical model that described the cover’s transient soil moisture profile. The successful performance of the cover is reliant on the long-term stable geochemical behaviour of the substrate used as cover material. Therefore, investigations were carried out to determine the geochemical properties of the cover materials constructed from benign waste rock using static and kinetic tests, with the objective to increase the level of certainty of the material’s benign characteristics. Consequently, the long-term performance of this water-shedding cover design is described in terms of the physico-chemical characteristics of its outflows.CITATION:Gonzales, C, Baumgartl, T, Edraki, M and Soliman, A, ?2014. Mine wastes as cover materials in a water-shedding soil cover in north-west Queensland, in Proceedings Life-of-Mine 2014 , pp 261–270 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 16, 2014

The western Cordillera of North America, including more than 99% of Alaska, is made up of an agglomeration of litho-tectonic terranes, some of which have undergone large rotations and (or) translations. The larger terranes can be broadly grouped into a small number of composite terranes based on affinities in their lithology, structure, and tectonic evolution. The terranes reflect repeated episodes of marginal rifting as well as formation of marginal arcs, island arc chains, back-arc basins, and oceanic plateaus since late Proterozoic time. Accretion to the continental margin occurred mainly from Middle Triassic through Early Cretaceous time. Major northward dispersal of terranes was largely during the existence of the Kula plate from about 85-55 Ma. Major rotations are the mid-Cretaceous opening of the Arctic Ocean basin with counterclockwise rotation of Arctic Alaska and Laramide oroclinal bending of western Alaska. The present complex Cordilleran geology along the northeast Pacific rim is a sum of these earlier accretionary processes together with continued Cenozoic faulting and deformation that has been superimposed upon the agglomerated displaced terranes over a broad segment of the continental margin.

Jan 1, 1990

By Nixon J. C, Reynolds C

Three principal features of the ore at Captain's Flat, New South Wales, tend to complicate concentration of the valuable minerals, these being:1. The ore occurs in three more or less separate bodies which vary in texture and mineral ratios. Mining of constant proportions of the three sections, or adequate blending of the ore, is not fully effective, and consequently the flotation section is subjected to feedof varying texture.2. The mineral association in the heavily pyritic ore is extremely intimate. Composite particles exist even at 20 micron sizeI, and probably finer.3. The copper content of the ore averages_about 0,6%, which is high enough to justify recovery of the chalcopyrite in a separate concentrate. A review of the metallurgical history of the mine shows that this feature has been the cause of the several major changes in flowsheet of the flotation section since the commencement of milling.METALLURGICAL HISTORYThe mine started production in January 1939, at the rate of 250 tons per day of sulphide ore, assaying 0·68% Cu, 6·52% Pb, 10·8% Zn, and about 1 dwt. Au and 2 oz. Ag per ton.

Jan 1, 1952

By M E. Watson

Minimising dilution and ore loss is an important part of ensuring profitability of a gold mining operation. White Foil open pit gold deposit is a low-grade deposit and therefore managing ore quality is a high priority. Ground movement through blasting can displace ore and waste boundaries up to 10 m from their in situ location and therefore requires stringent ore movement monitoring and adjustment. There are currently only two options for monitoring blast movement – utilising visual targets (commonly lengths of polypipe) but this has widely been replaced by electronic blast movement monitors (or BMM). Regardless of the technology used, the basic principle is to compare the pre- and post-blast locations of the targets to determine the movement of the rock mass during blasting, which is then used to determine the final location of ore and waste boundaries.The Blast Movement Technologies (BMT) BMM system has been used at White Foil since June 2014. The system has been effective and reliable during that time; however, the annual cost of using the BMM system is greater than other monitoring alternatives. As such, the open pit geology team conducted a study comparing the BMM system against the conventional polypipe technique. The objective was to quantify the profit and loss that would occur based on the ore block transformations from both methods. Eight blasts were selected where polypipes were installed in additional holes adjacent to the BMM monitoring holes. The resulting movement vectors from the respective methods were used to create post-blast ore blocks by transforming the in situ ore blocks. While polypipe is a cheaper alternative, the BMM system tracks ore and waste boundaries more effectively resulting in better quality control, enhanced ability to minimise dilution and ore loss thus maximising profit. For these eight blasts, it is calculated that the BMM system resulted in A$664 978 extra profit through a reduction of ore loss. The total cost of a yearly BMM package was recovered in the first two blasts of this study. The primary reason for the difference is that polypipe had a poor recovery rate of 32 per cent compared with 92 per cent for BMM at White Foil. Therefore, the data used to transform the ore blocks was less representative, resulting in inaccurate post-blast ore block boundaries when using polypipe.CITATION:Watson, M E, 2017. Blast movement monitors or polypipe? A study into cost-effective blast movement monitoring at White Foil gold mine, Western Australia, in Proceedings Tenth International Mining Geology Conference 2017, pp 433–440 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 20, 2017

By Pate W. T

This paper describes the development of a dynamic flowsheet simulator for comminution operations. Object oriented software design allows the handling of multiple ore types, blended into multicomponent feed streams. Software objects have been c

Jan 1, 1998

By B Cook, M Karakus, J Light, E K. Chanda

The aim of this research is to develop a model through which the appropriate paste recipe parameters, for example solid content and cement content, can be derived given the stope specific requirements such as stope dimensions, required strength and curing time. A large number of samples and uniaxial compressive strength (UCS) tests were conducted at the Angas Zinc Mine (AZM) paste plant and testing facility. Samples were varied in tailings solids content, cement content and sand content. The results of this testing were modelled to determine the UCS relationship to each of the parameters. The output of this modelling was an easy-to-use program that outputs the design mixture given the stope dimensions and required stope backfill-curing time. This allowed flexibility within the mining schedule for curing times of cemented paste backfill stopes. The optimised schedule using the stope specific mix design, when compared to the standard 14-day curing time used previously, resulted in a smoother weekly mine production schedule. For the modelled 12-week period (one quarter) the 14-day curing time would result in an eight-day shutdown of the mill. The cost for each shutdown is in the order of $125 000/d. Due to the unique nature of each mine’s tailings, this exact outcome would not be directly applicable to another paste fill site. However, the process in this report could be followed for another site to achieve a system similar to the output of this project. This would ultimately lead to a more optimised backfill and stoping cycle and a more optimised mine.CITATION:Chanda, E K, Karakus, M, Light, J, Cook, B and Harris, A, 2014. Optimisation of the paste fill cycle at Angas Zinc Mine, Strathalbyn, South Australia, in Proceedings 12th AusIMM Underground Operators’ Conference 2014 , pp 259–264 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Mar 24, 2014

By D MacKay

The Mt Wright Project is located near the town of Ravenswood in North Queensland and is operated by Carpentaria Gold – a wholly owned subsidiary of Resolute Mining Limited. Underground Development of the current Mt Wright orebody commenced in June 2006 and the first production ore was brought to surface in June 2007. The orebody is a rhyolite pipe containing fine-grained disseminated gold in a granite host rock. Ground conditions tend to be good to excellent throughout development, with some minor deformation experienced when stope-sized excavations are formed. The mine commenced as a sublevel open stoping (SLOS) operation with the intent to utilise development waste to back fill isolated upper level stopes while developing to the bottom of the known orebody. The mine plan intended to commence production with a bottom-up primary/secondary stoping retreat through the main orebody utilising cemented fill. Some challenges were faced during the initial production phase that included:•Ongoing underground diamond drilling and updating of the block model resulted in some issues reconciling the grade control results to the resource model. This was primarily due to the high variability of grade which in turn caused difficulties in accurately identifying areas of low and high-grade.•The cost of establishing and operating a cemented fill plant to achieve the planned extraction sequence of the orebody had increased significantly beyond initial estimations.•Geotechnical conditions such as stress orientations, ground behavior and response to the forming of excavations learned through the mining of the upper level stopes were different to the assumptions made during the initial design.A number of in-house and external reviews of the mining method were completed which has resulted in a revised mining plan. This paper will summarise the challenges faced and the implementation of the mine plan to date.

Mar 21, 2011

By M W. A Asad, E Topal, D S. S Sandanayake

Underground mine planning requires an optimal stope layout as a prerequisite for the definition of an optimal production schedule. The procedure to generate an optimal stope layout considers an orebody model and economic parameters as inputs. It evaluates all possible combinations of mining blocks and creates a set of stopes by satisfying the physical mining and geotechnical constraints. Thus, the procedure is computationally complex, and generating a solution to the problem is a challenge. This paper presents an implementation of a new heuristic algorithm that solves the stope layout problem. In two case studies, the algorithm achieves 11.2 per cent and 22.5 per cent superior solutions to the industrially available maximum value neighbourhood approach.CITATION:Sandanayake, D S S, Topal, E and Asad, M W A, 2014. Implementing a new heuristic approach to the underground mine stope layout problem, in Proceedings Orebody Modelling and Strategic Mine Planning Symposium 2014 , pp 243–248 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 24, 2014

By R Kjar

Globally, it is anticipated that the mineral sands industry will enter a period of short supply. Demand for both titanium dioxide and zircon is forecast to continue increasing, with new projects needed to come on-stream to fill the supply gap. Victoria is well placed under this scenario as a source due to the high quality of its mineral assemblage, its excellent resource grade and the globally significant size of its mineral sands resources.Australia’s mineral sands rich Murray Basin remains under-developed, especially at its extensive Victorian margins. Development to date has not progressed adequately for the reasons of technology difficulty, history of competition with other jurisdictions and the absence of a platform that requires development as a consideration for security of tenure. Victoria’s mineral sands potential is not just about the Murray Basin, in addition, there have been discoveries in the Gippsland Basin and prospective sites in the Gippsland Basin remain under-explored. Key problems included the lack of available ground for potential developers and the intellectual property of solutions to technological problems associated with the fine grained mineral deposits belonging to a previous developer (with patents now expired).As such, the timing is right to re-visit the potential of the Murray Basin as a site for long-term development with high returns based on current and predicted prices.In order to understand why Victoria’s earth resources in general, and mineral sands in particular, remain under-explored and undeveloped, the Department of Primary Industries initiated an internal review of its role in encouraging and supporting investment in the earth resources sector.As a result, the Victorian Government has committed to taking action to encourage effective ground turnover and acknowledges that a new focus on engagement with industry is needed to bring new investment to the State. The revision of the Mineral Resources (Sustainable Development) Act 1990 provides an opportunity for the government to better align its legislative processes with industry project lifecycles and facilitate access to valuable resources that currently remain undeveloped.Victoria has a track record in assisting projects reach development stage. Iluka currently has two operations in the State in addition to its mineral separation plant that is capable of processing HMC from its South Australian operations. Iluka is expected to ramp up its Murray Basin Stage 2 operations with the WRP mine scheduled to come on line in early 2012. Meanwhile, Astron is actively seeking partners for its Donald Mineral Sands project. The project is becoming increasingly attractive given the recent price hike in zircon; Astron has access to an estimated five to 6 Mt of zircon in its Donald WIM 250 deposit.Given its substantial and valuable mineral sands endowments, the State of Victoria should sensibly be the centre of future investment in project development. However, as previously mentioned this is currently not the case. The Government is therefore committed to implementing new measures that protect security of tenure but ensure that genuine companies can access endowments where they have a clear intent to work those resources.

Oct 5, 2011

The Imperial Smelting Process (ISP) for the simultaneous smelting of zinc and lead was developed at Avonmouth from the 1930's with activity intensifying in the late 1940's/early 1950's. Present operations are based around the No.4 furnace which was built in 1967. Development during the 1980's has been driven by the need to sustain operations at low metals prices and has been aimed at reducing manning whilst increasing output. Although hit by several major plant disruptions, progress has been steady, culminating in a ú10 million capital programme in 1988?89 to upgrade the operation. The most important technical developments, reflecting the needs of the 1990's have, in the sintering area, included improvements to feed conditioning and sinter quality, a 20% uprate in production capacity by debottlenecking, and pilot work leading to the installation of a Boliden-Norzink mercury removal plant. In the smelting area the ISP furnace has been rebuilt, with a redesigned bottom section to eliminate earlier operating sensitivities, and to achieve higher blowing capability, and at the zinc refinery the columns have been rearranged for more flexible operation and higher capacity.

Jan 1, 1989

Production from a major, deep orebody requires the construction of two 6 m diameter, 1000 m deep ventilation shafts over the next three years. Further ventilation upgrades have foreshadowed an additional 1500 m of 6 m diameter shafts beyond that. After reviewing the construction alternatives it was decided to raisebore the first shaft in one pass using Western Mining Corporation's 121R raiseborer and the Wirth sequential head. The significant cost and speed of construction potential of 6 m raiseboring justified the risks associated with this new technology. Large diameter sequential head raiseboring has only been carried out in South Africa. Over the last three years many lessons have been learnt and the technology has progressed to being considered feasible. Operating practice and the optimisation of raiseboring performance for specific ground conditions are the areas requiring further work. The development of large diameter raiseboring in South Africa and the site preparation and initial operation at Z.C. Mines are described. Comment on actual operating experience includes the geotechnical investigations, the raiseborer foundations, cuttings disposal and the drilling of the pilot hole which has progressed to beyond 450 m. Unforeseen difficulties with the verticality of the pilot hole and with mud losses illustrate the types of problems that can be expected.

Jan 1, 1988

By S Bluhm, LádeáOliveira, R Funnell

Taquari Vasouras potash mine (Vale Fertilizantes) has many interesting features including virgin rock temperatures of 50¦C at depths of 700 m. The mine has a relatively small shaft system with limited ventilation carrying capacity, which was not adequate to exploit the full extent of the deposit. This limitation was overcome by installing two large-scale recirculation systems with underground reconditioning centres. This paper describes this unique mine ventilation and cooling system and some of its history over the past two decades. The two controlled recirculation systems have been operating safely for some ten years and the use of large-scale recirculation has been a fundamental component in the increase of production and extending the mining further-and-further from the shaft centre. The recirculation systems have played a huge role in the mine profitability and comprehensively extending the mine life. The paper also discusses a number of novel design and operating features such as reverse running pumps for energy recovery. The underground chilled water system design required a number of special safety features in order to minimise the risk of water leakage since this could be catastrophic in a potash mine. This paper describes a good example of a mine in which the final ventilation and cooling system design ends up very different to what was envisaged at the greenfields stage.CITATION:Bluhm, S, Funnell, R and de Oliveira, L, 2013. Controlled recirculation and refrigeration at ValeÆs Taquari Potash Mine, in Proceedings The Australian Mine Ventilation Conference , pp 237-248 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 1, 2013

With the theme of û æUnderground Ore Handling SystemÆ, Kopanang Mine completed an extensive project on a specific system with technologies for the handling of ore from a dedicated drawpoint to the shaft system. The intended rail haulage tramming system had to be capable of handling the shaft design and Life of Mine (LOM) requirements. Kopanang is an AngloGold Ashanti gold mine situated in the province of the Free State in South Africa. In the Sotho language the name æKopanangÆ means to come together as a team. ItÆs an appropriate name given that 25 companies worked on this project. The future focus at Kopanang is to establish four mining levels between 3 to 4 km south-west of the shaft and two mining levels to the west. The mine has an expected life of almost 20 years and capital was approved in order to access this reserve to establish the infrastructure to handle the ore, hence this exclusive rail haulage tramming system of close to R40 million (SA rands), which took three years to construct. Apart from the fact that this system had to be capable of handling 6500 t per shift at a depth of over 2 km over a length of 3.2 km, some of the major considering factors were: safety, economic factors with improved labour productivity, efficiency and reliability, risk termination, and ergonomics. The system comprises two 20 t locomotives operating in a double header configuration from a dedicated draw point to a dedicated tip area for the reef and waste ore. With the objective of handling high speed and high capacity, this 200 t payload train is capable of running at 35 km/h powered from a 500 volt ac overhead line. Each loco consists of two 90 kW dc motors with ac/dc power conversion on the locomotive. For the system to operate at this speed, the rail system is constructed with Class 1 rails over the entire hauling distance. The tipping mechanism is unique and the span of 11 hoppers each with a load of close to 20 t is capable of tipping the pay load of 200 t in about 20 seconds hands free.

Jan 1, 2005

By L S. Shekhawat, M P. Roy, R K. Paswan, P K. Singh, A Joshi

Blasting in the mining industry is being transformed, and can no longer be treated as an art or a practice purely dependent upon experiences of individuals. Examples of key drivers that have demanded consistent and more accurate blast results are initiatives to control pit-wall damage to help mine steeper pit slope angles, to control damage to underground opening operating in close vicinity of the open pit mine. Such situation exists at Rampura Agucha open pit lead zinc mine, which is producing 5.7 Mt/a of ore and has started its underground part, which is slated to produce initially 2–2.4 Mt/a and 4.5 Mt/a in the near future. The open pit mine is currently working at 326 m depth and is designed to reach 421 m deep. It has been planned to operate the underground mine maintaining 50 m parting from the planned ultimate level of the open pit mine.Presently, open pit and underground mines are being operated simultaneously. The present average depth of underground working lies between 370 and 410 m below the surface level. Sometimes explosives up to 95 978 kg are being detonated in a blast round in open pit mine. These blasts are often apprehended as a danger to the safety and stability of underground openings. It was decided to document the impact of open pit blasting in the openings of underground workings, so that preventive measures may be taken for the safety and long-term stability of the underground mine. The impact of 86 open pit blasts has been documented in the underground openings and 258 blast vibration data has been recorded. The vibrations were recorded simultaneously in the roof, side walls and at floor levels. The highest levels of vibrations were recorded in the roof and the lowest levels at the corresponding floor levels. The pillars experienced lower level of vibrations than the roof. Blast designs were optimised at open pit mine to control vibration in view of long-term safety and stability of the underground openings. The vibrations generated due to detonation of explosives with shock tubes and electronic delay detonators have been recorded in underground openings for comparative assessment. Ground vibration recorded at roof, pillar and floor were analysed separately and threshold value of the vibration for the safety of underground workings has been determined based on the rock mass rating of the roof rock.CITATION:Singh, P K, Roy, M P, Paswan, R K, Shekhawat, L S and Joshi, A, 2015. Protection of underground mine structures due to adjoining open pit mine blasting, in Proceedings 11th International Symposium on Rock Fragmentation by Blasting, pp 279–288 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 24, 2015

By B Clements, G Lane

The operations and project environments are very different, but overlap in many areas. The development of mineral processing projects is goal oriented, is schedule focused and is a contractual environment. The operating environment for a mineral processing plant is oriented around longer-term commitments, focused on delivery against budget expectations, and an environment heavily influenced by long-term personal relationships, community relationships, and people issues.Further contrast is evident in the way expenditure is managed. Projects commit large amounts of money quickly to meet schedule-based objectives. Operations manage expenditure to minimise operating costs and are able to, or are forced to delay decisions on large expenditures. However, these two environments need to come together in many ways, ranging from greenfields plant handover to a new operations and maintenance crew, to day to day interaction and management of brownfields projects, often in close proximity.This paper considers the different perspectives people bring to projects and early operations, including the advantages and disadvantages of æoperationsÆ input to a project and models for managing value adding during project development, implementation and debottlenecking.CITATION:Lane, G and Clements, B, 2012. Operations versus projects - How do people think and what are the implications?, in Proceedings 11th AusIMM Mill OperatorsÆ Conference , pp 11-16 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 29, 2012

By G J. Lyman

The theory of sampling has progressed slowly over the last century. The concepts of correct sampling were known to mining engineers such as D W Brunton in the 19th century. It was recognised early in the 20th century that the Poisson distribution of particles carrying the target analyte was the key to the uncertainties between samples of a given mass. However, no efforts were made until the 1980s to determine the entire sampling distribution as a function of sample mass. The variance of sampling was made clear by Gy and others, but none attempted to determine the entire sample assay density function until J H Venter in South Africa applied the method of characteristic functions to the problem.Venter applied the method to a specific case of very low analyte concentrations in samples of very fine particle size where his assumption of constant sample mass was justified. When his general methodology is applied to the more general problem, it can be shown that the assumption of constant sample mass is no longer justified and leads to some anomalous results for sampling variance. Venter’s method can be expanded to allow for a statistically variable sample mass and to take into account the size distribution of particles that carry no analyte.This paper presents the basis of Venter’s work and shows how the approach can be easily modified to yield results for the variance that are consistent, for example, with the work of Gy. It is also demonstrated that the entire sampling distribution can be determined without undue computational burden when sufficient information on the material heterogeneity has been collected.CITATION:Lyman, G J, 2014. Determination of the complete sampling distribution for a particulate material, in Proceedings Sampling 2014 , pp 17–24 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 29, 2014

By J Kuva, M Parian, B I. Pålsson

One of the main factors affecting the suitability of an ore for autogenous grinding is the ore’s competency, ie providing enough critical stones for the grinding process. Several experimental test routines exist and are used for assessing the viability of the ore for autogenous grinding. However, very little attention is given to the generation of fatigue in large stones experiencing repeated shocks in the mill. To investigate this, large pebbles sampled from an industrial autogenous grinding mill running hard and soft ores were categorised based on the grinding energy. From the pebbles, small drill core samples were prepared and went through a series of fatigue cycle tests. Both hard and soft ores showed similar average resistance to failure in compression tests, but the hard ore had a consistent resistance with lower variations. The cores were scanned by XCT before and in-between fatigue tests at the highest reachable resolution, 1.5 µm voxel size. The outcome showed that a higher number of micro-cracks were visible in the soft ore compared to the hard ore. The frequency of micro-crack development in the soft ore may be the reason for its lower specific grinding energy compared to the hard ore. It is obvious that for realistic conditions in an autogenous grinding mill, stones are pre-weakened by fatigue before they fracture. Therefore, shortcut methods focusing only on running tests on fresh and small samples may operate in unrealistic conditions by ignoring the fatigue phenomenon. This is even more important for ores that are on the borderline to be considered as competent for autogenous milling.

Aug 24, 2022

By E Amini, M Scott

Grade Engineering® involves the planning, integration and operation of coarse preconcentration techniques to reject uneconomic material as early as possible in the mining value chain to improve the quality of ore delivered to mineral processing activities. These preconcentration techniques include screening for natural and induced deportment of grade to finer size fractions during blasting and coarse breakage, sensor-based measurements of grade and mechanised sorting at particle or bulk scales and coarse gravity separation. Over the last decade, the Cooperative Research Centre for Optimising Resource Extraction (CRC ORE), with the support of its participants, has developed a framework for the holistic evaluation of economic and production impacts attributable to these preconcentration techniques. The framework combines the characterisation of preconcentration responses, geostatistical modelling, process modelling and simulation of downstream and upstream production impacts and the optimisation of strategic mine plans to quantify changes in net present value due to different preconcentration strategies. This framework has been applied to evaluate preconcentration techniques at numerous metalliferous operations and can also be used to quantify changes in the environmental metrics for energy, water and steel consumption and emission, tailings and waste rock production. This paper collates the results of these Grade Engineering® studies to show the range and magnitude of economic and environmental impacts attributable to preconcentration. The studies have shown that rejection of uneconomic material prior to mineral processing activities can have a pronounced improvement in energy, water and comminution steel productivity, emission intensity and the profitability of metalliferous mining.

Nov 10, 2020

By S Zummar, A Van den Bulck, T De Staercke, T Van Rompaey

An increase of 22 per cent in lead usage is expected in the European Union by 2050. During lead refining, the Harris process is a critical step in which a salt melt is used to remove arsenic, tin and antimony. During this process, the caustic salt melt absorbs these impurities, requiring regular evacuation before saturation. Current metallurgical practices for: 1) determining the end point of the lead alloy involve time-consuming sampling and offline analysis, and 2) determining the end point of the caustic salt melt are based on subjective visual observations by the operator. In the context of Industry 4.0 concept, automating these processes becomes desirable, as smart sensors systematically collect real-time data in an unbiased manner. This research focuses on monitoring the Harris refining process using objective methodologies. Two different methodologies are investigated. The first methodology focuses on electrical conductivity changes of the caustic salt melt as function of Sb content. For this study, synthetic and industrial samples are used. A lab-scale electrical conductivity set-up was built to accommodate the aggressiveness of the salt melt. Initial findings suggest a promising relationship between electrical conductivity and Sb content in the caustic salt melt. Although the results are preliminary, the study provides valuable insights by enabling real-time measurements. The second methodology focuses on measuring the electromotive force (EMF) in lead doped with Sb at pilot-scale. Multiple probes are reevaluated for their effectiveness in Sb measurement. Ultimately, a partially stabilised MgO probe with Ni as a reference, without cardboard and copper protection caps, yields promising results. A correlation between EMF and Sb content is observed. However, repeatability issues arise due to possible wire interference at low temperatures. The results underscore the potential of advanced measurement techniques in optimising lead alloy production within the context of Industry 4.0.

Aug 21, 2024

By M J. Nugus

The Geita gold mines in north-western Tanzania have produced 5 Moz of gold from an estimated endowment of 15 Moz. They are generally classified as typical Archaean orogenic banded iron formations (BIF)-hosted gold deposits in banded iron formations as described by Goldfarb, Groves and Gardoll (2001); Neall and Phillips (1987); Phillips and Powell (1993) and Neall (1987). The controls on gold mineralisation have been reassessed to conclude that Nyankanga, and we conclude that Nyankanga, the largest deposits within the group, developed during a dynamic and protracted deformation history intimately associated with several stages of hydrothermal fluid flow and alteration. The fluid-induced fractures associated with gold mineralisation are primarily manifested as submillimetre to metre-scale fractures and breccias developed preferentially in rocks that have been previously deformed and altered by silicification or seafloor metasomatism. This realisation detracts from the exploration and mining strategies that would solely concentrate on fluid pathways and associated wallrock alteration and veining solely within the BIFs as hosts for economic gold mineralisation.

Aug 22, 2011