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By N. Hanief

This research involves the investigation of phase transformations in the platinum-chromium coated system. Single-layer 0.1 µm platinum coatings were deposited via electron beam deposition on 99.98 percent pure chromium substrates. Specimens were subjected to systematic heat treatment in a vacuum furnace at 900°C for up to 20 hours. Phase formation and the changes in surface morphology were investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM).Both CrPt and Cr3Pt phases are formed during heat treatment for different times at 900°C. Significant changes in the morphology of this coated system were detected after heat treatment at 900°C for 20 hours.

Jan 1, 2012

By I. Bock

This presentation describes a technique under development referred to as Selective Blast Mining. The technique involves millisecond sequential blasting. It applies to mines where the gold bearing conglomerate band is clearly demarcated, and separated from the waste rock in the foot and hanging wall. The width of the conglomerate band should be less than ± 0,7 metres. A research program was initiated in August 1994 by Drs RE. Robinson and I.E. Bock. The objectives were to develop new blasting methods that can reduce: ? the losses of gold in narrow reef stoping. Losses of gold can be as much as 10-15% ? and to introduce selective mining to reduce ore dilution with waste rock.

Jan 1, 1996

By F. J. N. Stassen

SYNOPSIS The effect of conditioning energy on the flotation of gold, U308, and pyrite was investigated in the range 0,1 to 100 kWh per tonne of dry ore for various combinations of conditioning time and impeller speed in a cylindrical con¬ditioning tank. It was found that, when the conditioning energy was increased to between 5 and 10 kWh per tonne of dry ore, the total recovery and flotation rate of the valuable minerals (expressed as Klimpel parameters) increas¬ed substantially. The Klimpel parameters are dependent on conditioning energy, but are independent of condition¬ing time or impeller speed (at constant conditioning energy). The Klimpel parameters of the gangue are indepen¬dent of conditioning energy.

Jan 1, 1991

By M. J. Southwood

SYNOPSIS Experiments carried out under atmospheric pressure and temperature (25°C) and sterile conditions show that the dissolution rate of nickel and copper from a pyrrhotite-pentlandite-chalcopyrite ore in a lixiviant of sulphuric acid is greatly enhanced in the presence of pyrite. At a pH value of 1,8 and in the presence of pyrite of equal mass to that of the ore, the recoveries of nickel and copper improved dramatically (21 and 80 per cent respectively). At a pH value of 4,0 the recovery of nickel was enhanced, but the chalcopyrite was refractory. A galvanic mechanism is probable, but cannot be proved from these experiments. The economic implications of the results are discussed.

Jan 1, 1985

By H. L. Monro

Contribution by B. K. Martust I congratulate the author on his interesting paper. In my view, the establishment of the level at which South African gold output is at some kind of optimum is an interesting though somewhat academic exercise. Contribution by D. M. Hawkins* The thesis of the paper is a very interesting one, but, before it is used as the basis of any firm proposals to restructure the mining industry, which changes may be irreversible, one should be very sure that the basis of the calculations is sound. Contribution by P. J. Niewenhuizen* The hypothesis advanced by Mr Monro that the demonetization of gold in August 1971 introduced a major new policy variable, namely the supply-pricejdemand-price relationships, into the decision making process touches on a matter that has never really been given serious thought by the industry. Contribution by B. G. Kingsman* As a co-worker on the development of an econometric model for supply and demand in the world gold market with Mr H. L. Monro, it would perhaps be useful for me to make some comments on the various points raised in the discussions on his paper.

Jan 1, 1984

By T. Bohmer, L. Auret, N. Pillay, Z. Horn, P. Rambalee, A. Haasbroek

As part of a broader digital technology-enabled transformation programme, a major mining company is systematically implementing Advanced Process Control (APC) solutions and associated instrumentation throughout their operations. This paper highlights the approach and benefits of this holistic approach for a specific instrumentation installation, and APC installation at a South African coal processing plant. For the coal processing plant under consideration, a systematic approach was followed. Process sections/units are considered from upstream to downstream processing. APC solutions are designed for each process section and each process section is interrogated in terms of availability of sufficient process measurements to ensure stable, capable, and ultimately, optimised performance. Where insufficient process measurements are available, instrumentation upgrades are implemented. Finally, APC solutions are implemented, and evaluated in terms of productivity, safety, health, and environmental benefits. For the flotation section, an opportunity was identified to install froth sensors. The installed froth sensors provide measurements on froth velocity, bubble size, height, colour, and stability. The improved visibility that the froth sensors provided on the flotation process resulted in quick gains in terms of productivity: for example, instability in the feed to the flotation section could be quantified. This resulted in targeted process troubleshooting in an upstream thickener, and subsequent improvement of process stability, and reduced feed variance. The measurements from the froth sensors were further integrated in an APC solution. Proportional mass pull contributions per cell and per line can be inferred from the froth sensors, serving as controlled variables, while pulp level set points serve as the manipulated variables. On-off tests indicated that the advanced process control solution provided increases in yield and product quality.

Sep 1, 2021

By Nelson Sánchez

The Los Bronces Development Project (LBDP) was approved in October 2007 by the Anglo American plc Board at a capital cost of some US$1.74B, and is scheduled to be completed by the end of 2010. The project represents a big step forward for the Los Bronces mine since it will increase the treatment rate by 140%, the mining rate by 64% and almost double copper production during the first four years of the project. This economy of scale will also position Los Bronces as a much bigger and efficient mining operation, better prepared to face adverse market scenarios and allowing Anglo to consolidate its position in base metals. The project addressed numerous scope alternatives such as plant capacity vs mine capacity, cut-off grade strategy to maximise value based on the existing flotation and leaching process, cutback strategy, etc. Main infrastructure aspects of the project are as follows: ?Dump area with 2400Mt capacity for waste and low grade material ?Mining equipment: 1 x electric shovel, 12 x 300t trucks, 1 x drill ?Primary crusher: 60? x 89? ?Three new power lines (144MW capacity) ?Grinding plant at 87kt/day nominal capacity (includes a 4.3km tunnel with a regenerative conveyor belt) ?Grinding plant: 1 SAG mill 40? x 25?, 2 ball mills ?Slurry pipeline (52 km from grinding to flotation plant) with five choke stations ?Flotation plant (rougher, cleaning, regrinding circuits and molybdenum flotation). The history of Los Bronces started in 1867 when it was discovered. In 1978 ENAMI (Government company) sold Los Bronces to Exxon for US$112M. The same year a snow avalanche destroyed San Francisco Flotation Plant. In 1979 the plant was rebuilt at 4.9kt/day and from 1979 to 2002 several plant expansions were made up to 54kt/day capacity. In 2002 Anglo acquired Los Bronces for US$1.3B. The 2002 resource and reserve statement showed reserves at 459Mt at 1.02%CuT and resources at 780Mt at 0.80%CuT. The 2007 statement shows reserves at 1,480Mt at 0.67%CuT and resources at 1,644Mt at 0.45%CuT. Defining the size of a plant expansion is the key challenge that any expansionary project faces. The scope of this paper is a general review of the project, describing all the mining techniques that were used to define the best options that maximise value. In this context, a range of plant capacities (from 58 to 230kt/day) combined with a range of mining capacities (from 83 to 166Mt/a) were evaluated in detail, defining for each option a mine plan, Capex and Opex, and cut-off grade strategy for flotation and leaching processes and the associated Net Present Value (NPV) that was used as the selection criteria. The Los Bronces mineral resources potential provides good growth opportunities for the mine beyond LBDP implementation, offering an exciting invitation to continue studying new initiatives that maximise the value of this deposit.

Jan 1, 2008

By E. M. W. Skinner

Various models of near-surface kimberlite pipe emplacement have been proposed over the years. These include a top-down, phreatomagmatic model, a bottom-up, embryonic pipe model and three top-down explosive dyke models. AU of these models consider kimberlites as essentially the same rock type. However, different kimberlites have different pipe shapes and contain different rock types with very specific mineral assemblages and textures and therefore are likely to have been emplaced by different processes. Some authors have considered local geological differences as the principal reason for the contrasting geology but others argue that, while geological differences might contribute locally the petrographic peculiarities of particular kimberlites may be due mainly to inherent compositional differences specifically in the ratios of juvenile CO2 and H2O.

Jan 1, 2010

By S. T. Johansen, B. T. Løvfall, T. Rodriguez Duran, J. Zoric

A methodology for building pragmatic physics-based models is here adapted to predict the erosion of ladle linings in the steel industry, in order to support operators when deciding whether the lining can be used safely for another heat. A defective lining may allow 140 t of molten steel to spill, with disastrous consequences for workers and plant. The adopted work flow for the development, challenges faced, and some model results are presented. One key learning outcome is that model development should allow time for maturing the process understanding, as well as for many iterations by ‘questions-responses and actions’ at various stages in the model development. Good interaction between the development team and industry case owner is an important success factor. Combining or extending the model with the use of machine learning and cognition-related methods, such as knowledge graphs and self-adaptive algorithms, is discussed.

Apr 16, 2024

By O. S. Tinkler, K. C. Sole

"Although the first large-scale application of copper recovery by solvent extraction took place in Zambia in the early 1970s, it is only in the last decade that this technology has become widely employed in this part of the world and is now a mainstay unit operation in copper hydrometallurgical flow sheets. The mineralogy of the ores of the African Copperbelt, and hence the characteristics of African leach liquors, differs significantly from those in Chile and the southwestern USA, where copper solvent extraction has had a long and successful history. These differences provide operators, metallurgists, reagent vendors, and engineers with many challenges: new approaches are needed to adapt solvent-extraction technology for successful implementation in this region. This paper examines typical operating practice in the African Copperbelt, discusses differences compared with other parts of the world, and looks at some of the challenges and opportunities presented by these flow sheets. IntroductionFollowing the success of the Rancher’s Bluebird and Bagdad solvent extraction and electrowinning (SX–EW) operations in Arizona in the late 1960s, the Tailings Leach Plant at Chingola, Zambia, became the first large-scale copper SX plant in the world, commissioned in 1974. Despite the equipment design now being outdated, this plant still continues to operate successfully, indicating the versatility and adaptability of this technology. Today, there are some 75 copper SX operations worldwide with cathode production above 10 kt/a. The top ten producers currently account for about 40% of the global 4.3 Mt/a SX–EW copper production. South America (predominantly Chile and Peru) is the largest copper cathodeproducing region, with annual production of some 2 Mt. The Central African Copperbelt (Zambia and the Democratic Republic of Congo (DRC)) is second, with cathode production of 1.2 Mt/a, and North America (USA and Mexico) third, producing close to 0.8 Mt/a Cu (Solvay Cytec data, 2014). The remaining 0.35 Mt/a comes from all other regions combined (referred to as ‘Rest-of-World’)."

Jan 1, 2016

By E. Pothas, P. R. Jochens, L. B. McRae, D. D. Howat

SYNOPSIS The phase equilibria, viscosities and sulphur capacities of titaniferous slags were determined in the composition range of CaO = 30 to 0 per cent, MgO = 0 to 30 per cent, SiO2 = 19.69 per cent, AI.O. = 13.12 per cent and TiO2 = 37.19 per cent. The phase equilibria were determined by high temperature microscopy, the viscosities were measured using a rotating outer cylinder viscometer and the sulphur capacities were evaluated from the results obtained by equilibrating the slag in a gas stream of CO, CO2 and SO2. The behaviour of these titaniferous slags under reducing conditions was examined. Possible use of the slags for aggregate, or slag-cement, and the possibility of extracting the TiO2 are discussed. CONTENTS INTRODUCTION PHASE EQUILIBRIA VISCOSITIES DISCUSSION OF THE PHASE EQUILlBRIA AND THE VISCOSITY VALUES EFFECT OF REDUCING CONDITIONS SULPHUR CAPACITY DISCUSSION OF THE SULPHUR CAPACITY VALUES POSSIBLE USES CONCLUSIONS ACKNOWLEDGEMENTS REFERENCES INTRODUCTION The latest phase in the exploitation of the mineral wealth of the Bushveld Igneous Complex is the erection of a plant by the Highveld Steel and Vanadium Corporation Limited near Witbank to produce steel and vanadium-rich slag from the titaniferous magnetites occurring in this rock formation. These titaniferous magnetites occur as segregations in the gabbro body and the TiO2 is mainly present within the structure of other constituent minerals but also occurs in smaller amounts as ilmenite and ulvospinel. The vanadium is thought to be present in the iron oxide phase due to isomorphous replacement of the iron. Until very recently, it was feared that the high titania content of these titaniferous magnetites would militate against their value as useful iron ores. However, the design of an integrated plant to produce both steel and vanadium-rich slag, and in which the iron-making process is conducted in submerged arc furnaces instead of in

By C. Snyman, M. Le Roux, Q. P. Campbell, S. Engelbrecht

Due to the ultrafine particle size required for effective processing of chromite ores, dewatering of the concentrates presents a challenge. It is not uncommon for the ore to have elevated moisture contents even after dewatering, which must be reduced to required levels of between 8% and 10% by mass for further processing. Contact sorption drying has shown promise in test work on fine coal. This method was used to study the dewatering of chromite on a laboratory scale using 3 mm spherical activated alumina ceramic beads as a sorbent. Three different sorbent-to-chromite mass ratios, namely 0.5:1, 1:1, and 2:1, were tested with different process conditions, including dewatering in a stationary and a rotatingl bed. The experimental work showed that it was possible to achieve the target moistures in less than 10 minutes, irrespective of the sorbent-to-chromite ratio used. Ratios of 1:1 or higher, however, proved to be the best. The sorbent reusability at mass ratios of 1:1 and 2:1 were therefore tested. With a 1:1 mass ratio, the sorbents could be reused for three cycles, while with 2:1 ratio, the number of cycles increased to six. The sorbent-to-chromite mass ratio used had a significant influence on the required contact time and the reusability of the sorbents.

Oct 3, 2023

By V. W. Lumadi, S. Nyasha

The mining industry has yet to fully accept and embrace the strategic role of technology and innovation in successful business planning and execution. In this study, we empirically determine the factors that influence acceptance of technology solutions in the mining industry in South Africa, assess critical success factors influencing adoption of advanced technology in the South African mining industry, and explore challenges faced by the mining industry in South Africa in adopting advanced technology in its operations. Thematic content analysis is employed in the data analysis. Results show that critical success factors to the adoption of mining technology include learning culture, knowledge sharing, high labour costs, and behaviour of other firms in the industry; commonly identified challenges include inadequate engagement with external stakeholders, uncertainties, the cyclical nature of the sector, and high risk related to the adoption of unproven technology and performance systems focused on volumetric production. The study encourages mining companies to implement usage of technology. This can be properly done through regular engagement with the Minerals Council South Africa.

Apr 14, 2024

By C. Hartford, T. Holmes

Bulk-solids handling systems are often the most over-looked component and thereby weakest links in a processing plant’s value chain. Since their performance can dictate that of the entire operation, they actually deserve special attention. When designing a liquid handling plant, density and viscosity are well known and commonly used as design parameters. Bulk solids however, differ. While the design process is similar, the relevant parameters in handling bulk solids are instead friction, cohesive strength, compressibility, and permeability. These then vary depending on the mineralogy, particle size distribution and shape, moisture content, storage time-at-rest, temperature, and consolidation pressure. With so many variables, it becomes important to characterize each individual bulk solid across the full range of representative process conditions within the handling system, plant wide – or if you are not very lucky, suffer the consequences of poor material flow. Measuring flow properties and applying them correctly in bulk solid handling system design reduces project risk, saves significant capital, and drastically increases throughput, especially when done in the early stages of a project. Keywords: Flow Properties, Bulk Solids, Process Conditions, System Design

Jan 1, 2020

"Chairman: Prof A. E. H. BLEKSLEY Rapporteur: Prof J. ELBRONDPanel Members: Prof J. C. Griffiths, Prof T. E. Hawkins, Mr A. C. Langton, Mr M. Splaine, Mr A. WeissThe reasons for failure of computer applications in the mineral industry and the direction of future developments.The Chairman opened the discussion by elaborating on the disappointment felt by some authorities with the lack of progress in the application of computers in the mineral industry during the last ten years, and posed the question to the panel : 'Do you agree that the computer age has not come up to expectations?'Mr Langton said that although there seemed to be a tremendous amount of brainpower applied to the theoretical side, he thought that the production men had not got all the help from computers that could have been given to them. The computer, said Prof Griffiths, is as yet a new tool which should not be used to do old things in old ways. To learn to use the computer will take time. After all, he said, it had taken 400 years after the introduction of the printing press to achieve general literacy, and perhaps it will take 40 years after the introduction of the computer to achieve `numeracy'.In Mr Weiss' view, the reason for the feeling of disappoint¬ment lay in the focussing of attention on the computer. The blame, if any, lay with the people surrounding the computer, that is, the analysts and programmers, to whom the emphasis should be shifted.Prof Hawkins said that he thought that some applications of the computer in the mineral industry had been successful, such as, for example, the compilation of payrolls. Reasons for failures in other areas were to be sought in the fact that the people connected with computers had failed to realise that they were merely part of a system. They had not understood the power structure of the organization which their work tended to change, and were therefore not prepared for the inevitable conflict with the production men.In Mr Splaine's view the production man had not received the assistance he could have had from the computer people because he may possibly not have allowed this to happen.Prof Bleksley concluded from these opinions that the promise which computers had ton years ago had not been fulfilled and added that the opinions expressed by the panel had intruded on his next question which was: 'Is the reason for this that people are involved?Prof Hawkins elaborated on his previous theme, namely, that of computer people in relation to management. Com-puter people, he said, were trying to impose change on management but were not prepared to share the responsibility for these changes. In fact, they wanted their work to be distinct and separate, and, as far as management was concerned, changes would be made when management believed that these would be less agonizing than no change at all."

Jan 1, 2014

By A. Atta-Quayson

Since 2012, Ghana has been implementing local procurement regulations in the mining sector to broaden and deepen linkages between mining and other sectors of the economy. The regulations have been implemented in collaboration with the mining industry. This paper offers an in-depth analysis of how the local procurement regulations and related initiatives have been implemented so far. Primary data gathered with semi-structured interviews and secondary sources of data indicate a steady improvement in both in-country procurement and local manufacturing of inputs for the mining industry. There are, however, some challenges relating to tariff structure and support (financial and technical) for local suppliers and manufacturers to meet high standards and demands of the mining industry. This calls for a well-thought-out strategy and programme of activities to sustain and improve on progress made.

Feb 2, 2022

By Johanna van Deventer, Sean Scott, Rene du Preez, Steven R. Izatt

In order to meet the stringent specifications associated with the production of LME Grade A cobalt cathode, producers need to ensure that a number of impurities, including Cd, are removed from the advance electrolyte to ppb levels (~0.1 mg/L). Conventional options include ion exchange using amino methyl phosphonic acid resin and solvent extraction using D2EHPA. More recently a Cd-selective resin, employing Molecular Recognition Technology (MRT), became available from IBC Technologies, Inc. These three potential unit operations were evaluated in parallel at Mintek. MRT was identified as the most technically feasible option. Results obtained on a cobalt advance electrolyte, containing 55 g/L Co, 6 mg/L Cd and 60 g/L Na2SO4, are presented in this paper.

Jan 1, 2007

By J. Petersen, M. Reuter, E. Asselin, M. Becker, N. Uys

In order to meet society’s ever-increasing demand for metals and address the numerous technical, economic and environmental challenges within the current mining context, a holistic approach to process design, which is grounded in mineralogy, is needed. This would ensure that the impact of varying process mineralogy (and associated chemistry) on technical considerations and the associated economic implications and environmental consequences are taken into account upfront. This investigation focuses on the commodity zinc due to its strategic value coupled with limited resource availability and the wide variety of substantially different process technologies in existence. As the most commonly processed zinc ores contain zinc sulphides, the mineralogy/chemistry of these ores and their associated process routes will be discussed. The findings have been generated through the analysis of two case studies, Teck’s Trail Operations (British Columbia, Canada) and Hudbay Minerals’ Flin Flon Operations (Manitoba, Canada). The flotation of zinc sulphide ores to produce concentrates with varying mineralogy, represents the starting point for both case studies. The hydrometallurgical process routes for the further refining of zinc and other valuable metals include roast-leach-electrowinning (RLE), and zinc pressure leaching (ZPL). The effect of process route choices on primary metal recovery (Zn), coproduction of other base metals (Cu, Pb), potential for other valuable metal production (Ag, Au) including less well known, but increasingly important trace elements (In, Ge), and the production of other by-products (H2SO4, S0) are discussed. The economic and environmental implications of these aspects will also be considered. It is concluded that a quantitative modelling approach must be taken where waste management is integrated into process system design and simulation as a key unit operation. Keywords: Zinc Sulphide Processing; Design Decisions; Mineralogy

Jan 1, 2020

By C. Tokoro, T. Kato

The objective of this study is to improve the shrinking core model for particles with a particle size distribution and clarify the activation mechanism of rare earth elements dissolution by mechanochemical activation. To achieve this objective, the method, called the doubly integrated micromodel, was applied for a shrinking core model in this study. This method consists of integrating the batch leaching rate of a single particle over the distribution of both feed particle size and reactor residence time to arrive at the fraction unleached. The usefulness of the shrinking core model improved by doubly integrated micromodel was confirmed by comparing it with a shrinking core model. To apply the shrinking core model improved by doubly integrated micromodel to rare earth elements dissolution from weathered residual rare earth ores by mechanochemical activation, leaching experiments were performed for grinding samples by planetary ball milling. The reaction equation of mechanochemical reaction by planetary ball milling for weathered residual rare earth ores was investigated by x-ray absorption fine structure analysis. As a result of a kinetics study, the rate-determining process of leaching changed from reaction to diffusion reaction control by planetary ball milling. Based on these results, it was revealed that the main mechanism of activated rare earth elements dissolution from weathered residual rare earth ores was a mechanochemical reaction by planetary ball milling. Keywords: Mechanochemical reaction, particle size distribution, shrinking core model

Jan 1, 2020

By D. Bessinger, J. Rabe, J. Zietsman, C. Coetzee, P. H. Lamont, J. Muller

The UCAR® CHILL-KOTE? freeze lining concept combines wall cooling with carbon and graphite refractories of higher thermal conductivities to ?chill? the refractory lining by transferring heat from the refractory lining. Effective sidewall water cooling, together with the efficiency of the heat dissipating conductive refractories, lowers the temperature of the lining to below that of the molten process materials. This causes a layer of slag and process metal to solidify or ?freeze? and form a protective ?skull? which completely coats the refractory hot face. Once formed, the slag skull insulates the refractories, reducing heat loss and protect the lining from erosion, chemical attack, thermal shock, and other stresses. The result: extended life and greatly improved refractory performance. The Ilmenite smelting process depends on the presence of a solidified slag skull to protect sidewall refractory material from chemical attach by molten slag. No known refractory material is able to withstand this corrosive material. To date, UCAR has not applied their Chill Kote ? technology in the ilmenite smelting industry. This paper revolves around the results obtained from conducting an ilmenite smelting campaign on a 500kW DC open-arc furnace with a UCAR designed refractory system. The purpose of this test was to establish the effects such a lining has on refractory wear and the reduction-smelting process. Proper thermo-couple management enabled the authors to monitor lining wear for the duration of the campaign. Prior to the pilot-scale campaign, modeling work was completed to evaluate the feasibility of applying UCAR® CHILL-KOTE? technology to ilmenite smelting furnaces. The successful operation of a pilot-scale furnace equipped with the UCAR® CHILL-KOTE? lining as well as concise modeling suggest that it should be a viable option to consider for an industrial-scale furnace.

Jan 1, 2007