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By B. Dyck, L. Verhelst

"Colloidal silica in Key Lake’s Solvent Extraction (SX) feed solutions has presented an operational problem for the mill throughout its history. The colloidal silica stabilizes aqueous continuous emulsions, resulting in elevated solvent losses and operational downtime. Through the years, many attempts have been made to solve this problem, but no viable solutions were found. By revisiting an idea dating back to the 1979 feasibility study and re-evaluating it under current operating conditions, a practical solution was achieved. This paper discusses Key Lake’s history around colloidal silica removal, starting with coagulation using a polyethylene oxide polymer (PEO), and ending with coagulation using a polyethylene glycol (PEG) polymer. The results of a mill trial using POLYSIL® RM1250 introduced at doses up to 300 ppm into the counter current decantation (CCD) circuit to clarify SX feed solutions are discussed with a focus on the benefits to SX.INTRODUCTION Colloidal silica has historically been a significant operational problem in the Key Lake mill. Silica originates from clays in the ore as well as concrete backfill intermixed with the ore resulting from the mining method used at Key Lake’s ore source, the McArthur River mine. The silica is dissolved as silicic acid into solution in the mill’s sulphuric acid leaching circuit. Once in solution, silicic acid polymerizes (Hearn, Smethurst, & Boskovic, 2016) forming a fine suspension of stable colloidal particles. These silica colloids are unaffected by flocculants and sand filtration reporting to the pregnant leach solution (PLS) as a fine turbidity in solution. Silica concentrations typically ranged from 700 to 1200 mg/L Si in the PLS fed to SX. Throughout Key Lake’s history, silica interactions in the Solvent Extraction (SX) process have made SX a mill bottleneck and a source of significant reagent costs."

Jan 1, 2018

By S. Deonarain, L. S. Schultz

"This paper details the process and methodology followed to rehabilitate a rectangular ventilation shaft, situated in the Free State region of the Witwatersrand Gold Fields in South Africa. The shaft consists of seven compartments where self-mining of the sidewalls had taken place and damage to the decayed steel work in the shaft had taken place, thus limiting access down the shaft. The paper will provide some insight into the successes and challenges encountered during the project and may provide some learnings for future projects of a similar nature. INTRODUCTION The ventilation shaft forms part of the Phakisa Mine, situated in the Welkom area of the Free State province of South Africa, and is located in the Southern part of the Witwatersrand Basin, one of the world’s largest known and richest gold deposits (Figure 1).As is typical in South African gold mines situated in the Witwatersrand basin, the shaft is 1 770 metres deep (below collar). The shaft was sunk during the early 1940’s and comprised a rectangular shape with 7 compartments, used for both rock hoisting and men and material winding, respectively, with a single lift “Mary-Anne” compartment. Early in 2003, the mine decided to change the shaft from a downcast hoisting shaft to an up-cast ventilation shaft. The conveyances, ropes, winders and headgear (head frame) were removed and replaced with a high volume fan delivering 323m³/s of air at a pressure of 4.2Pa on surface. The up-cast velocity in the shaft was 6.5m/s, however this reduced significantly with the scaling of the shaft and the restrictions at shaft bottom. Although Harmony had converted the shaft from a downcast service shaft to an up-cast ventilation shaft some years back, the shaft steel work in the barrel of the shaft was left intact. Over the years, the steelwork in the shaft had decayed (rust and grime) and portions of this steelwork fell down the shaft. Concurrent with the decaying steel work, portions of the shaft lining had collapsed and it was getting progressively worse."

Jan 1, 2019

By K. H. Concannon, K. I. Hindle

"The use of simulation modeling in the primary metals industry (including mining, smelting, and metals processing) is expanding as significant cost-benefits can be realized by companies employing capital intensive processes. The economic scale and complexity of operations found in this industry is well-suited to applications using this ""what-if' computer modeling technique, ranging from proof-of-concept projects to testing facility design or configuration, and determining resource requirements. More recently this technique is being used to support on-going planning and scheduling for operations using the simulation as the engine to derive the best schedule. With increased computer processing capability, deterministic models are now being developed to capture the workings of a production system or conversion process, allowing real-time monitoring and scheduling of these operations. This paper presents a sample of some recent discrete-event simulation modeling applications that demonstrate the capability and benefits of this technique in the primary metals industry. These include the use of simulation to support the long-range planning of underground mining operations; the modeling of a metals supply chain network that employs a multi-modal distribution system; the scheduling of a metals coil finishing process using a deterministic simulation model; and a more detailed description of the use of simulation to model furnace and converter aisle activities within a smelter operation in Northern Canada."

Jan 1, 2007

By CIM Standing Committee

The CIM Definition Standards on Mineral Resources and Reserves (CIM Definition Standards) establish definitions and guidance on the definitions for Mineral Resources, Mineral Reserves, and mining studies used in Canada. The Mineral Resource, Mineral Reserve, and mining study definitions are incorporated, by reference, into National Instrument 43-101 – Standards of Disclosure for Mineral Projects (NI 43-101). The CIM Definition Standards can be viewed at mrmr.cim.org. Readers should be aware that reports written by persons issuing technical reports that disclose information about exploration or other mining properties to the public in Canada are governed by a number of securities regulations.

May 10, 2014

By Gurupraveen Ramanathan

Shallow-dipping orebodies (45°–60° dip) present significant challenges for underground longhole stoping, particularly due to limited gravity flow, drill misalignment near the footwall, increased potential for dilution from hanging wall overbreak, and deviation from drill string sagging at shallow angles. These geometrical and operational constraints often lead to unblasted ore wedges and excessive overbreak when standard practices are applied. This study develops a structured, data-driven framework to optimize longhole stoping in such conditions by integrating five key focus areas: (1) mining method selection, (2) stope and drift design, (3) drill and blast optimization, (4) equipment selection, and (5) performance evaluation. The suitability of longitudinal longhole stoping was validated for narrow vein geometries using orebody analytics and prior case studies. Geometric modeling was employed to determine optimal stope height (15–20 m) and stope width (1.5–2.5 m), with drift widths adjusted based on orebody dip to maintain drill access and minimize unbroken ore. Drill and blast design emphasized sequential blasting over multi-ring methods to improve void control, reduce wall damage, and enhance fragmentation. Specific burden and spacing guidelines (e.g., 1.8–2.3 m burden; 2.5–3.0 m spacing) were applied based on stope width and dip angle, and patterns were selected based on geometry—dice-5 for narrow stopes, and 3-hole rows for wider stopes. Drill rigs—including top hammer and ITH models from Sandvik, Epiroc, Boart Longyear and CMAC-Thyssen—were evaluated for compatibility with drift dimensions and alignment accuracy. Equipment was matched based on dip, drift width, and the ability to access the footwall at shallow angles. Sensitivity analysis quantified how changes in geometry, drilling accuracy, and blast design affect ore recovery, dilution, and operating cash flow. Results show that tailored drift and stope geometries, combined with proper blasting and rig selection, can boost ore recovery to over 95% and reduce dilution to below 5% in optimal conditions. This methodology offers a practical and economically optimized solution for shallow-dip mining scenarios.

May 4, 2025

By I. Southern, S. Kelebek

"Smelting furnace bricks contain significant quantity of base metals trapped in refractory material. A series of flotation tests were carried out on samples of old bricks from Sudbury area to examine upgrading behaviour for recycling purposes. Depending on the grind size used nickel recoveries varied from 60 to 90.6% with corresponding grades of 20% and 14.7%Ni. There is a trade-off between nickel and copper. The nickel has responded well to fine grinding, however, the copper recovery suffered from it. Mineralogical characteristics and flotation behaviour of the brick material are discussed in reference to those from the primary ore. INTRODUCTIONMineral processing is well recognized as a mature technology not only for the mining industry, but also for the environmental industry for the purpose of remediation and recycling. Materials available for recycling are usually the products of many years ago. There are multiple stake holders in this area. In general, when the processing results in a product that can be reused or sold, the company carrying out the remediation makes a profit, while the regulators and the public are pleased due to a cleaner environment. From these points of view, there have been many papers published over the years on various mineral processing techniques applied to separation of many different materials including from mining and metallurgical industries (Wilson et al., 1994; Tsunekawa et al., 2005; Saikia et al., 2012).Flotation may be viewed as the backbone of the mining and metallurgical industry since its invention for separation of solids from one another almost a century ago. It is capable of recovering a variety of finely divided different solids following their liberation from each other. Its versatility and highly competitive nature in terms of cost per tonne of material processed, accounts for its occasional uses in the environment engineering area. In the mining industry, flotation is the standard method used for the sulphide ores. It can be applied as a bulk flotation and/or differential flotation. Bulk flotation, which refers to co-flotation of several components from their source, is most suitable for environmental cleanup objectives. Desulphurisation of various plant tailings is a typical example of this (Benzazzoua et al., 2000)."

Jan 1, 2012

By Jeremy G. Berg, James B. Mulligan

"There is a very small fraction of wireless experts in the world with experience in underground installations and an even smaller fraction that have experience specific to building mine shafts. This is why in 2009, Redpath created its own system to meet the demands specific to shaft construction. Today, after a dozen shaft installations and several design iterations, Redpath has the expertise and experience required to implement a proper wireless system in any shaft configuration.This document will explain multiple proven wireless communication designs optimized for shaft construction and suitable for permanent use. This includes line of sight installations up to 1200m, short range mesh networks, and the latest patent pending Integrated Leaky Feeder Mesh Network. Additionally, this document will explore the lessons that Redpath learned in its effort to interconnect the people and tools needed to build a mine shaft.INTRODUCTIONAfter a decade of research, several design iterations and a dozen application examples, Redpath has resolved two wireless network architectures to best serve mine shaft construction projects.The long range line-of-sight (LOS) wireless network is the most cost effective and easiest to install, but requires an unobstructed line of sight between the working area and the shaft collar. As such, long range LOS is best suited for ventilation shafts or during the first phase of shaft sinking, before the shaft is equipped.Alternatively, a mesh network uses radios installed at pre-determined intervals in the shaft and on each conveyance. A wireless mesh uses antennas to bridge intervals between shaft radios, whereas Redpath’s integrated leaky feeder mesh network (patent pending) bridges these intervals with radiating cable, commonly referred to as a “leaky feeder” cable. Both of these mesh configurations can provide continuous reception for hoist conveyances travelling in shafts without line-of-sight, making them ideal for shaft equipping and even permanent installations in both mine shafts and lateral drifts.BACKGROUNDHoist operators receive operating commands using what are commonly referred to as “bell signals.” These instructions are delivered in a series of coded pulses on a spring returned pull cord or push button that is typically hardwired back to the hoist operator’s control room from one of many locations in the mine shaft. During the construction phase of a traditional mine shaft, a worker riding inside the sinking bucket would have to reach out to a pull cord installed on the shaft wall to send a stop command to the hoist operator. Today, Redpath’s modern shaft sinking projects use fully enclosed personnel carriers to protect the workers riding inside, specifically preventing workers from reaching out into the shaft while the hoist is in motion. The enforcement of this safety feature on all shaft projects in 2008 forced the engineering group at Redpath to find a suitable wireless solution for hoist communication to facilitate shaft construction.THE IDEAL COMMUNICATION SYSTEM FOR MINE SHAFT CONSTRUCTIONIdeally, the shaft communication system should not transform the tools to which the miners have grown accustomed. It should support the push-to-talk functionality of traditional VHF handsets and the standard belling system that has been used for decades. Additionally, it should be able to support a vendor independent framework upon which new devices and features can be added. The following paragraphs summarize some of the important requirements Redpath has identified.Support for voice transmission: Low latency is critical to prevent jitter during voice transmissions. The system must be compatible with commercially available mobile handsets and support several simultaneous conversations with the ability to broadcast a voice message to all users on a select channel using a “push-to- talk” microphone and loudspeaker.Transmission of PLC data: Low latency is required to"

Jan 1, 2019

Cansolv® S02 Scrubbing Technology was described in a paper in Copper/Cobre 03. Four years on, the technology is operating at a full scale production facility.Hindustan Zinc Limited expanded their capacity by installing the AUSMELT process. The process proceeds through smelting, slag reduction, slag cleaning and holding stages sequentially in the same vessel, resulting in widely varying off gas characteristics. The off gas is suitable for treatment is a conventional acid plant for a modest proportion of the day, but at other times produces off gas too high in S02 to be discharged to atmosphere. Cansolv® S02 Scrubbing Technology was identified as a means of effectively removing the S02 down to low levels from the off gas during all stages of the pyrometallurgical process. Furthermore, the Cansolv® S02 Scrubbing System Technology produces high purity S02 that allowed for the captured S02 to be directed to an existing acid plant, avoiding the capital cost of new acid making capacity.

Jan 1, 2007

By R. Rumpold, J. Antrekowitsch

"The continued increase of the automobile production leads to a higher platinum, palladium and rhodium (PGM) demand. Due to the high value of the PGMs the recycle of these metals from automotive catalysts is of special interest. Pyrometallurgical processes, which are only focused on the PGMs, represent the state of the art of automotive catalysts recovery. However, hydrometallurgical recycling processes offer additional recovery of other valuable metals and compounds. The method presented in this paper is based on a combination of hydrochloric acid and hydrogen peroxide to dissolve the valuable metal fraction which can be precipitated afterwards.INTRODUCTIONPlatinum and the corresponding metals from the PGM group, especially palladium and rhodium are well known as catalytic active materials. They support chemical reactions which are inhibited. This effect is used to decrease the amount of harmful compounds like hydrocarbons, carbon monoxide or nitrogen oxides in automotive exhaust gases. The generation of these toxic substances is based on incomplete combustion, which in turn is caused by non-ideal conditions in the combustion chamber. Catalytic converters minimize the harmful compounds by supporting the following Reactions 1 – 3 (Votsmeier et al., 2009).CO + ½ O2 ? CO2 (1)CnHm + (n + ¼ m) O2 ? n CO2 + ½ m H2O (2)2 NO + 2 CO ? N2 + 2 CO2 (3)Platinum and palladium are very effective for the oxidation (Reactions 1 and 2), while rhodium supports the decomposition of nitrogen oxides by carbon monoxide (Votsmeier et al., 2009). The classical three way catalyst was a platinum – rhodium combination with a Pt:Rh ratio of 5:1 (Hagelüken et al., 2005). Today the platinum, palladium and rhodium ratio is highly variable and strongly depends on the engine type as well as on the car producer. Diesel engines are operated with a super stoichiometric air addition in comparison to spark ignition systems. Therefore the exhaust gas composition and off gas temperature is different. Based on the high oxygen amount, diesel engines produce less carbon monoxide and hydrocarbons but more nitrogen oxide in contrast to gasoline engines. This leads to various requirements for the catalytic converters."

Jan 1, 2012

By M. Myllymäki

"Pre-treatment of mill feed in a minerals processing plant enables for higher production efficiency per ton of product, reduction of consumables and diverting mineral feed types. Sensor based particle sorting allows for pre-concentration of the run-of-mine (ROM) material prior to other concentrating process. Various sensors provide different responses from the minerals in measured particles. The capability of “accepting” or “rejecting” particles based on sensor responses is investigated in specific test work for each project. Modern sorting machines use pneumatic actuators to divert the reject particles from the material stream. This paper discusses the incorporation of ore sorting test work in processing and plant design. When taking the effects of a sorting circuit into account early in the process planning phase, the downstream process can be adequately sized and impacts evaluated. Potential benefits include but are not limited to increased head grade, lower tonnage to the mill, increased mining operations, removal of deleterious elements and changed properties in the process feed. In a case study we present the Keliber lithium project in central Finland. The plant will produce 9000 tons of lithium carbonate per year from a spodumene ore. Ore sorting and flotation tests were carried out in laboratory and pilot scale. Process models were designed and simulations performed using Outotec’s HSC Chemistry Simulation software. Changes in the flotation performance (grade, recovery, impurity levels) were simulated with and without the pre-concentration of the ROM material. The metallurgical performance and mine economics of the different operational scenarios were evaluated using the Ore-Met optimizer module of the simulation software.INTRODUCTION Challenges in the recent years such as declining ore grades, increasing energy prices, scarcity of water and increasing environmental regulations raise the demand for more efficient processing technologies. Sensor based sorting offers a method for pre-concentration or waste rejection at an early process stage. The technology analyzes each rock particle separately for their unique physical and chemical properties, and diverts the particles into separate material streams by high pressure air jets. Successful implementation relies on ore heterogeneity, differential sensor response and suitable feed preparation."

Jan 1, 2018

By L. Van Wyk, J. Fernandez, J. Suarez, L. J. Diaz, A. Uria, D. Breeuwer

"Ventilation is an essential component of any underground mine, playing a vital role in ensuring the health and safety of workers, and a mine’s continuous operation. At a time when mining companies are increasingly having to move to deeper underground operations in pursuit of high-grade ore-bodies, the search is on for more efficient ventilation systems that will allow mining to be carried out at even deeper levels whilst ensuring the protection of workers and the maximisation of productivity through temperature management and the lowering of energy costs. Mining companies today are looking for innovative ways to deliver new technologies and procedures to enhance their mine’s profitability. Energy consumption by mine ventilation systems is higher than ever due to stringent specifications of underground equipment (primarily combustion engine emissions), air quality standards and mining at deeper levels which all require more powerful ventilation systems. With energy costs associated with operating ventilation systems being a mine’s second-highest cost of production after labour, finding the optimal ventilation solution is critical to a mine’s performance. Proper fan design remains a major factor in reducing capital expenditures (CAPEX) and operational expenditures (OPEX), which means that there are compelling reasons for making use of comprehensive factory testing at full power before fans are dispatched to site to simulate the mine’s current and future design requirements, and thus verify the fan’s effectiveness in ‘real’ conditions.INTRODUCTION A primary mine fan is considered the heartbeat of the entire mine ventilation system, drawing fresh air from the surface and providing a safe environment for miners. A ventilation system’s lack of performance often leads to a reduction in acceptable air quality levels for underground working operations and can potentially have an adverse impact on production rates."

Jan 1, 2019

By Anoush Ebrahimi

Mining dilution is one of the most important factors affecting the economy of mining projects. Ore losses and dilution are present at all stages of mining and while several models can investigate the influence of dilution it is its quantification that poses the most serious challenge (Pakalnis et al., 1995). This paper introduces a methodology to quantify dilution factor in open pit mines. The proposed approach makes use of general mining software available in most mining companies. Therefore it is amenable to most mining operations and provides a readily available tool for understanding mining dilution for operators and consultants. To illustrate the methodology the author uses an example from a hypothetical mine. Dilution increases the operating costs in the mill by increasing the tonnage of material to be milled. In addition to its direct impact on short term income of a mine, dilution causes significant changes in other factors that on the long term reduce the overall value of the project. For example, it prolongs the mine life by reducing mill?s effective capacity. It also reduces the feed grade. In most cases, lower feed grade means lower mill recovery. Dilution also increases the cut-off grade which in turn reduces the overall ore utilization of a mine. In some cases, to take advantage of economies of scale, mining operations tend to plan for higher mining rates. Moving to a larger scale of operation means less selectivity, hence more dilution. This is true for all kind of deposits. High level and uncontrolled dilution may ultimately defeat the purpose of increasing production rates. If not impossible in theory it is nevertheless extremely difficult and expensive to eliminate dilution in practice. Some amount of dilution is practically unavoidable in most mining operations (Scoble and Moss, 1994). Although completely avoiding dilution may be impossible, we can measure and control it. By better understanding the root causes of the dilution and planning accordingly, it can be controlled and reduced. While we do our best to identify and calculate all the other cost items of a project, no matter how small, it is common to make general assumptions about dilution instead of quantifying it. It is common to assume a general dilution such as 5% for massive deposits and 10% for tabular shape deposits. While these figures may be a good starting point in early stages of mining studies, it does not take in to consideration the complexity of the problem. Dilution factor varies within a single mine for different benches and zones. This is due to changes we see in grade distribution and shape of ore body. It also varies based on commodity price. It is necessary to make sure that these variations are taken into account when designing or evaluating a mine. Dilution varies in different mines based on the deposit characteristics, operational aspects and economic cut-off grade. For instance, shape of the deposit, bench height, equipment size, and market conditions will have an impact on the level of dilution in a mine. It is paramount for mining projects to have a better understanding of dilution right from the beginning. In times like today, where mining operations must operate at peak efficiency, it is even more crucial to be able to calculate and have a better grasp of all the parameters influencing the economics of a project including dilution. In order to produce better project evaluations, dilution studies should be an integral part of any project.

Aug 1, 2013

By B. Haneman, J. A. Gorst, W. Slabbert

"The Bayer process involves the digestion of bauxite in caustic liquors at high temperature and pressure. Typically the digestion section of the plant involves the heating of liquors up to the digestion temperature followed by flashing of the digestion product to atmospheric pressure with the flashed steam used to pre-heat the incoming cold slurry. Despite the heat recovery, the digestion process is a high consumer of energy. The application of tube digestion technology in such plants has resulted in significant improvements in refinery energy efficiency with associated benefits of process simplification and refinery flow sheet capital cost reduction. This paper reviews the potential application of this technology to other metals within the non-ferrous industry.THE BAYER PROCESSA typical Bayer flow sheet is shown in Figure 1. The raw feed material bauxite (containing aluminium hydroxide as gibbsite Al(OH)3 and boehmite AlO(OH)) is digested in caustic liquors (caustic soda is the solvent) at high temperature and pressure. This process extracts the alumina and silica and any carbon present on the ore. The slurry is then flashed down to atmospheric condition allowing for heat recovery from the flashed vapour and producing slurry supersaturated in alumina.Following the digestion process the mud is removed via thickening and then pressure filtration to remove fine particulate and produce a clarified liquor with dissolved alumina in solution. The resulting pregnant liquor is then cooled allowing the alumina in solution to precipitate as aluminium trihydrate Al(OH)3. The precipitated hydrate is then filtered and washed and classified into fine and coarse fractions. The fine material is returned to the precipitation process as seed while the coarse fraction is calcined at high temperature to produce alumina. The filtrate from the filtration process (spent liquor) is then heated by the incoming pregnant liquor before being fed to an evaporation process which produced the strong caustic liquor required in the digestion process. Finally, the mud from the thickening process is washed to recover caustic and then fed to tailings ponds. The washer overflow is then mixed with the digester product to increase super-saturation."

Jan 1, 2012

By D. E. Deegan, G. Holcroft, T. P. Johnson

"The rising cost of extracting metals from existing traditional deposits, increasingly stringent environmental regulations and a greater awareness of corporate social responsibility issues are all factors in stimulating the examination of mine tailings and small-scale alluvial deposits as a potential source of new raw materials. Furthermore, despite tougher economic times the demand for commodities remains strong, in no small part as a result of the growth of the world’s emerging economies.This combination of social and economic factors looks set to continue in the long term which will encourage greater recovery of materials from previously ignored sources such as mine tailings and ores from alluvial deposits.An expansion in the recovery of useful materials from mining-related activities is likely to require the use of robust and innovative techniques that have a built-in degree of future-proofing; DC plasma technology is one such technology.As a result of its ability to separate the valuable metal and minerals from the waste material while destroying hazardous compounds, Tetronics’ DC arc technology offers an alternative approach to resource recovery from a wide range of mine ores. Harmful cyanide compounds and the vast quantities of water used in conventional hydrometallurgical processing are avoided when plasma processing is adopted. DC arc technology also brings additional benefits, including: the extremely effective destruction of organic materials, the conversion of the inorganic material into a re-useable aggregate and the high tolerance of the process to fine and dusty materials. This paper presents details of Tetronics’ DC arc technology as one of the key pyro-metallurgical solutions available for the recovery of valuable materials from traditional mine ores and tailings, as well as giving specific examples of how the technology has been successfully employed in the recovery of enriched slags, ferroalloys and other metals."

Jan 1, 2016

By G. W. Norval, V. G. Papangelakis, G. A. Moldoveanu

Smelting has been the primary method of treatment for refractory copper sulfide concentrates such as enargite (Cu3AsS4), but the pyrometallurgical processing generates elevated levels of volatile arsenic. The present research investigates a novel hydrometallurgical process of oxidative dissolution of enargite at ambient conditions in the presence of chlorine dioxide (ClO2), a very powerful oxidant generated in solution by the reaction between a strong acid (HCl or H2SO4) and sodium chlorite (NaClO2). The effects of initial oxidant concentration, particle size, agitation speed and temperature on dissolution kinetics and copper extraction were investigated. It was found that a stoichiometric ratio of ClO2:Cu3AsS4 = 9:1 were needed to completely and congruently dissolve the mineral with fast kinetics (<15 minutes) under ambient temperature. The dissolution extent (metal extraction) increases with increasing ClO2 concentration and decreasing particle size of solids, but is not influenced by temperature or agitation speed.

Jan 1, 2014

Infrared spectroscopic data collected using HyloggerTM technology is being used to assess the mineral composition of Archean iron ore bedrock and Cenozoic detrital units in Western Australia’s Pilbara region. Analysis of infrared spectra enables quantification of: (1) composite iron mineralogy, (2) composite clay mineralogy, (3) hydrous silicates and (4) carbonate mineral abundances. Stratigraphic and rock mass unit logging of core has identified several detrital and bedrock units recognisable across the Pilbara. However, due to alteration related to mineralisation, weathering and later stage precipitate overprinting, it can often be difficult to assess the detrital-bedrock boundary and the occurrences of specific geotechnical units in the detritals and bedrock, particularly when using non-core drilling techniques and traditional geochemical assays. Infrared spectroscopic data collected concurrently on core from several sites has shown distinct correlation against existing unit subdivisions and associated geochemical parameters. Where infrared spectroscopic data have also been collected on rock chips recovered from reverse circulation infill drilling, these correlations allow robust geological and geotechnical models to be developed based on the typical mineralogical-geochemical signatures. The geotechnical sub-units identified in core can be readily distinguished using the various iron and clay minerals captured by the HyloggerTM technology as opposed to total iron, potassium, and alumina captured by geochemical assays. Further, some of the minerals targeted by infrared spectroscopic analysis (eg gibbsite, white mica, vitreous goethite) and their ubiquitous presence as the products of weathering, assist in recognition of various ancient weathering surfaces and help to define the origin of the material, whether bedrock or detrital. Overall, HyLogging of core and chips allows important mineralogy focussed data to be captured at minimal additional financial outlay. Correlations against geochemical unit identifiers are robust both within deposits and between deposits. Significant improvements in the confidence of geological and geotechnical models are attained.

Jan 1, 2015

By G. P. van Greunen

"The rehabilitation of underground excavations has been undertaken as long as mining has existed. The conventional methods have proven to be dangerous, time consuming and expensive. During the construction of Styldrift Mine at Royal Bafokeng Platinum several vertical and horizontal excavations had to be rehabilitated. With a zero tolerance attitude towards working in unsafe conditions, together with a non-negotiable timeline to construct and ramp up the mine, the project team could not rehabilitate these excavations using conventional methods. This paper details the approach used to rehabilitate excavations using remote methods and how it was adapted to suit varying operating conditions and requirements - ensuring that no person ever entered an unsafe excavation before it was fully rehabilitated and safe. INTRODUCTION Styldrift Mine is an expansion project of the Royal Bafokeng Platinum group. It is located in South Africa in the North West Province some 10 km south of the Sun City resort (Figure 1). The mine consists of a twin shaft system (Main Shaft and Services Shaft). Capital construction of the shaft and associated infrastructure started in 2009 and is projected to be completed during 2020. The designed steady state production capacity of the shaft is 230 ktpm of Merensky ore. Production ramp-up commenced in 2017 with steady state production set to be achieved 36 months later in the fourth quarter 2020.Merensky Reef was intersected at a depth of 600 m below surface and the shaft design has a mean mining depth of 630 m. The project was approved for execution in 2008 on the basis of a suitable mine design and bankable feasibility study. One of the main excavations that required rehabilitation was an underground reef silo, Silo 4. It is a key piece of infrastructure on the critical path to allow steady state production at Styldrift Mine to be achieved. During construction excessive scaling within the silo along its 64m length necessitated urgent rehabilitation to be able to meet the ramp-up schedule. The criticality and urgency of these excavations prompted the project team to reduce the risk of failure while ensuring safe and cost-effective rehabilitation. This paper will focus on the rehabilitation of Silo 4 while capturing the essence of the learnings of all the excavations that were rehabilitated remotely."

Jan 1, 2019

By A. Oja, M. Lahtinen, P. Salonen, B. Saxen

Most of the secondary and low grade zinc raw materials cannot be treated successfully by either conventional roasting - leaching - electrowinning (RLE) process or even by atmospheric direct leaching process. The problems arising especially from high impurity content of these raw materials can be effectively solved by implementation of the solvent extraction process. The utilization of solvent extraction process has been demonstrated by Outotec with raw materials like Waelz oxide, crude zinc oxide and zinc containing concentrator tailings. Based on batch and continuous test work it has been shown that SHG quality zinc can be produced even from the lowest grade raw materials. Impurity control in the solvent extraction process has been examined. The solvent extraction process is the key feature of the whole zinc plant for such raw materials. However, design of the entire zinc process including neutralization and bleed treatment is important for optimization of investment and operation costs of the plant. Very careful evaluation of the zinc process with modern simulation tools is essential. The optimized Outotec zinc process ensures a sustainable and profitable process containing minimal effluent and requiring little residue treatment.

Jan 1, 2014

By A. M. King, J. M. Neilsen

"Roughness at varying scales is an important component of the shear strength of discontinuities. Small scale roughness can be assessed in drillcore and through laboratory testing of drillcore derived samples. Large scale roughness, or waviness, also plays an important part in peak shear strength and a number of methods for its incorporation into defect plane strength models are presented.A number of methods for capturing waviness data from exposed faces are reviewed. A method is presented for deriving waviness from downhole televiewer data, which is shown to be significantly more accurate than structural data derived from core logging. The method is based on work undertaken in the highly anisotropic bedded units of the Hamersley Province, Western Australia where televiewer surveys are routinely undertaken. Values of waviness are derived through a review of variation in dip resolved in the direction of the slope face. This method allows design engineers to incorporate large scale roughness in defect plane shear strengths at the design stage.INTRODUCTIONThere are a number of constitutive models currently being applied by rock mechanics practitioners in calculating defect plane shear strength parameters, such as Patton, Barton – Bandis and Hencher [1, 2, 3]. Most of these shear strength determinations are typically undertaken by determining the base or residual friction angle, and applying corrections for small and large scale surface roughness."

Jan 1, 2015

By T. Xue, A. Singhal, D. Wrana, I. Mihaylov

"At Vale's Thompson Nickel Refinery, the copper and arsenic in the nickel electrolyte are removed by precipitation using H2S, generating a sulphide precipitate containing about 40% Cu, 8% Ni, 2 to 4% As and 30% S. This residue has been typically stored in impoundment ponds within the plant site. Various options for reprocessing it have been investigated over the years. One of the options involved oxidative pressure acid leach, whereby over 95% Cu, Ni and As were extracted. More recently, an atmospheric alkaline sulphide leaching process for selective removal of 70 to 90% As was developed and mini-plant tested. After alkaline sulphide leaching, the dissolved arsenic is precipitated as stable basic ferric arsenate (BFA) with the addition of ferric sulfate, while the low-arsenic Cu/Ni sulfide is suitable for processing in Vale's operations elsewhere in Canada.INTRODUCTIONVale’s Thompson Nickel Refinery was commissioned in 1961 and currently it has the capacity to produce about 56,700 tonnes per year of electrolytic nickel as cathode slab and rounds products. A sulphate and chloride mixed electrolyte is used in the Thompson refining process and it typically contains 75 to 85 g/L Ni, 50 to 60 g/L Cl, 90 to 120 g/L SO4 2-, 25 to 30 g/L Na and 8 to 9 g/L boric acid. The main impurities in the Thompson anolyte are copper, cobalt, arsenic, iron and lead.The simplified Thompson electrolyte purification flowsheet is shown in Figure 1 (Oliver & Wrana, 2009, Goble & Chapman, 1986); it consists of precipitation of copper, arsenic and lead with H2S, followed by nickel replenishment with ground matte and acid and removal of cobalt and iron with Cl2 and NiCO3."

Jan 1, 2012