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By Y. Rama Murthy, Amit Ranjan, Pankaj Satija, Sunil K. Tripathy

"Chromite ore is one of the essential raw materials for ferroalloy and steel industry. Boula-Nuasahi belt of Sukinda region, Odisha, is the only resource of chrome ore in India. The Indian deposits are typically characterized as ferruginous and siliceous type ores. Chrome ore is generally mined by open cast mechanized mining method in these areas. The run-off-mine (ROM) ore from the various mines is sent to beneficiation plant via stack yard for further up gradation. The chrome ore beneficiation plant (COB) has two major circuits: comminution (feed preparation) circuit and beneficiation circuit. In the comminution circuit, the ore is reduced to <1 mm size ( for complete liberation of chromite) from -220 mm size in stage wise crushing (primary and secondary crusher) followed by screening and single stage grinding in a ball mill. Fraction having size <1 mm is further upgraded in the beneficiation circuit to produce three different concentrates having specific chemical composition and Cr: Fe ratio. The beneficiation plant is a complex circuit comprising of combination of unit operations (spiral concentrator, Floatex density separator, hydrocyclone, wet shaking tables). In the recent years the overall performance efficiency (grade and recovery) of the beneficiation circuit got affected with numerous changes in the run-off-mine ore quality (physical and chemical), mineralogical composition, etc.In this article, attempts made for improving the performance of chrome ore beneficiation circuit is discussed. The approach adopted and practical problems encountered while the process were also highlighted. The results of the trials has shown an improvement in the performance of the cyclone (d50 : 56 µm – 40 µm) and chromite losses into tailing to <12%.INTRODUCTIONChromite has a wide range of application, from refractories to metallurgical industries, and from chemical to non-ferrous alloy industries. Chromium ore (Fe2+, Mg) [Cr, Al, Fe3+]2O4) occurs exclusively in rocks formed by the intrusion and solidification of molten lava or magma which is very rich in the heavy, iron containing minerals such as pyroxene and olivine. With the richness of silica and iron, the chrome ores are broadly classified as siliceous type and ferruginous type. Pure chromite with composition FeCr2O4 is rare because magnesium usually substitutes for ferrous ion and aluminum and ferrous ion substitutes for chromium. Generally the associated gangue minerals are talc, quartz, hematite, goethite, limonite, gabro, serpentine, anorthosite, dunite, pyroxinite, etc. Around 96% of the chromite ore production is consumed for metallurgical applications of which 94% is converted into different grades of ferrochrome i.e., high carbon ferrochrome and charge chrome as shown in Figure 1. Stainless steel being the leading consumer of ferrochrome, any change in the dynamics of the stainless steel industry impacts overall chrome ore demands significantly."

Jan 1, 2016

By L. H. Cole

Introduction The increasing importance of the gypsum industry in Canada is evidenced by the fact that the production has increased from 473,129 tons valued at $809,632 in 1909 to 1,205,846 tons valued at $3,622,007 in 1928, an increase of over 155 percent in quantity, and of 347 percent in value, in the 20-year period. Although the export trade in crude gypsum still forms a large proportion of the industry, it is gratifying to see that the home consumption is steadily increasing, and while the percentage of the crude gypsum mined that is manufactured into the calcined products in the country is only 16.8 per cent, its value is practically 50 per cent of the total gypsum production of the whole country. It is to be hoped that each succeeding year will see an increase in the amount manufactured in Canada, and, with the steady growth of the country and a serious endeavour to capture a part at least of the world market in gypsum products, the outlook for the industry is decidedly promising. The value of gypsum as a commercial commodity has been known from the time of the early Egyptians; in fact its value for certain purposes has been known so long chat the date of the discovery of its peculiar properties is unrecorded.

Jan 1, 1930

By Patricia J. Dillon

Established in 1997, Prospectors and Developers Association of Canada Mining Matters (PDACMM) is a registered charitable organization dedicated to providing Earth Science education to grade school students. Through the development and distribution of educational programs and materials, PDACMM informs students of Canada?s geology and mineral resources as well as promoting awareness of the importance of rocks, minerals, metals and the mining industry. PDACMM also co-ordinates with other charitable organizations and government agencies to provide support or to work in tandem with them and reach as many young people as possible. Although PDACMM became a charitable organization in 1997, it actually has its? roots in 1994 when the Grade 7 program Mining Matters/Une Mine de Renseignments was developed to help teachers bring geology and mining into the classroom. Over 2100 of these resource kits were distributed to teachers across Ontario during the period 1995 to 1998. This unit won national recognition when it received the prestigious Partnership Focus award from the Conference Board of Canada for ?promoting science literacy for the world of work?. Due to the phenomenal success of these kits, a Grade 4 kit entitled Deeper and Deeper/Aller au Fond Des Choses was developed in 1998 in response to the opportunity provided by the new Ontario curriculum released at that time. Over 2600 of these kits were distributed throughout Ontario and there is a substantial waiting list of teachers hoping PDACMM will be able to raise enough money for another print run.

May 1, 2002

By B. Das

"Computers have been used extensively in the mineral industry in exploration, reserves calculation, mining technology, mineral processing, etc. With respect to coal mining, there are also various applications for evaluating rock slope stability of open pits, design of open pits, underground operations, mine ventilation, ground control, data processing and management information, operations control and certain technological applications. Mine ventilation appears to be the field in underground coal mining touched on most; on the other hand, underground coal mining methods evaluation is represented only sparingly.It is therefore essential to review the status of the computer in underground coal mining methods evaluation in order to define its scope for further application. The paper discusses the roles of the mining engineer, programmer, computer operator and analyst as well as that of the computer. The important parameters will be identified and discussed along with their application for different underground coal mining methods, with their individual unit processes. Mainly, longwall face operations have been covered. Although many models have been of academic interest, they can be considered as important steps in a transition stage which will be followed by more practical applications for computers for underground coal mining method evaluations in the future. This calls for a coordinated effort from all concerned."

Jan 1, 1981

By M. Piche

The western part of the Hauy Formation of the Opemisca Group, occurring near the town of Chapais, is described in this paper. As it has been defined previously, the Formation is composed of a succession of subaerial andesi tic lava flows with some interbedded proximal volcaniclastic sediments. Towards the East, these volcanics yield to coarse grained fluviatile sediments having similar composition to the interbedded lavas. Further east, the composition of these sediments is more arkosic with dioritic and tonalitic fragments. It is proposed that these arkosic sediments are a part of the Stella Formation which has been described by Dimroth et al. (1982).

Jan 1, 1984

By V. Silins, J. Tameling, R. C. Cook

"A general review of the wear problems encountered in the mining industry is presented and current practice for wear protection systems is reviewed.A new concept in wear protection is described and compared to alternative systems. Utilization of conventional stud welding technology and abrasion-resistant wear studs is shown to be a useful supplement or substitution for conventional techniques. Operating life of many consumable components can be increased by up to four fold. The technique is highly portable for on-site field application or can be used in shop environments.Details of the wear protection model and metallurgical properties of the wear component are also reviewed. Laboratory wear test data are reported to supplement field test performance or to screen potential alloy compositions for application in specific environments.A Review of Wear Problems and Wear ProtectionThe emphasis on wear protection has increased in recent years because of the increasing impact of the potential savings in time, materials and energy. A 1974 German study concluded that attention to tribology, the study of friction and wear, could save approximately $3 billion, and a study in the U.S.A. at the same time put the figure at $100 billion of which $20 billion was for materials. A more recent American study put the energy component of the potential savings at $16.2 billion per year. A recent British study estimated the total potential savings in the U.K. as $1 billion per year, with the largest savings coming from lower maintenance and replacement costs ($500 million), lower breakdown costs ($250 million) and increased machinery life ($200 million). These three major contributions are all potentially accessible in the mining industry."

Jan 1, 1982

By Earl T. Hayes

This paper briefly reviews the laws enacted in the United States governing the coal miner. It discusses amendments to the Coal Mine Safety Act and describes the provisions of the Metal and Non-Metallic Mine Safety Act.

Jan 1, 1969

By Deni Pageau, Deni Caron

"This paper describes the operations of the open pit and emphasizes particular aspects of Les Mines Selbaie. The open pit as well as its related services were incorporated into a complex which includes an underground mine and a concentrator. The equipment was chosen with the objective of auto-sufficiency during each phase of mining. The paper outlines the organization and the methods used in each step of mining, notably: drilling, blasting, loading, transporting and crushing. The responsibilities of the Engineering Department are also outlined from the conception of the open pit to the latest follow-up methods. A short resume of the results which have been obtained as well as suggestions for improvement are provided.Layout in Consideration of Main SiteThe A-I zone deposit is located I km from 8 zone. Open pit mining of A-I zone required the regrouping of different services to those already existing.I. The crusher was placed in an area close to the concentrator in order to minimize the length of the conveyors and to provide space for the crushed ore reserves (50000 tonnes).2. The location of the service building (warehouses, mine offices, maintenance, engineering and geology) raised a few problems. Because of the multiple services provided therein , it was impossible to fulfill all the requirements, and the garage in itself is located a fair distance from the pit. Added to this inconvenience is the fact that heavy equipment regularly travels throughout the main yard.3. The storage of explosive magazines has been changed to obtain more surface space and meet government regulations.4. A space has been provided for minor repairs in the garage used during exploration. A trailer was installed next to the garage to provide a lunch room for the employees working at the open pit."

Jan 1, 1990

By K. Morin, C. -Y. Hon, G. Lachapelle

"Air-sampling results suggest drill operators working inside environmental drilling cabs at an open-pit gold mine in Nunavut, Canada, are at risk of exposure to asbestos and silica (quartz). The authors installed RESPA® CF Vortex HyperFLOW® units, which showed promising results under laboratory conditions. The goal was to evaluate the effectiveness of these units under actual working conditions. Personal and area air sampling was conducted in drilling cabs with and without the unit and a Wilcoxon rank-sum test was performed to compare the results. Particulate concentrations were significantly lower in drill cabs with a unit installed than in those without.RÉSUMÉ Selon les résultats d’une campagne d’échantillonnage de l’air, les foreurs travaillant dans des cabines de forage environnemental dans une mine d’or à ciel ouvert du Nunavut, au Canada, risquent d’être exposés à l’amiante et la silice (sous forme de quartz). Les auteurs ont installé des unités RESPA® CF Vortex HyperFLOW®, lesquelles of frent des résultats prometteurs en laboratoire. L’objectif est d’évaluer l’efficacité de ces unités dans des conditions de travail réelles. Des échantillons de l’air inhalé par le personnel et dans les aires de travail ont été évalués dans des cabines de foreuses équipées ou non de cette unité ; un test de Wilcoxon (également appelé test de la somme des rangs de Wilcoxon) a été mené afin de comparer les résultats. Les concentrations particulaires étaient considérablement plus faibles dans les cabines de foreuses équipées d’une unité que dans celles en étant dépourvues.INTRODUCTIONGenerally, mining operations are associated with a variety of occupational hazards. In an open-pit gold mine in Nunavut, Canada, drill operators are routinely exposed to asbestos (primarily amosite) and silica (quartz)—two naturally occurring substances in the ore that is to be drilled (Table 1). Inhalation is the primary route of exposure for these two hazards, which are associated with respiratory health effects such as asbestosis and silicosis, respectively. In addition, asbestos and silica are classified as human carcinogens by the International Agency for Research in Cancer (2001, 2011). Given the toxicity of these two agents, it is imperative that precautions be taken to minimize the risk of exposure of the mine’s workforce. To address this matter, the mine has an exposure-control plan, which includes the provision of personal protective equipment, personal hygiene facilities, training, and a medical surveillance program. Furthermore, the mine performs occupational exposure assessments or air sampling on a regular basis because the morphology of the ore changes rapidly with respect to asbestos and silica content."

Jan 1, 2017

"Bay d&apos;Espoir is in the approximate center of the south coast of Newfoundland. The geology of the area can most conveniently be considered in terms of three units: (1) an Ordovician or older polydeformed terrain termed the Little Passage Gneisses; (2) a Lower-Middle Ordovician volcano-sedimentary sequence assigned to the Baie d&apos;Espoir Group; and (3) granitoid intrusive rocks of mid-Paleozoic age. Mineralizing events accompanied the formation of the latter two units.The Baie d&apos;Espoir Group comprises a dominantly sedimentary sequence of pre-Middle Ordovician shelf and distal turbidite sediments deposited on the eastern margin of Iapetus. A significant volcanic component is, however, present in the Isle Galet Formation, consisting of up to 30% felsic volcanic rocks interbedded with sedimentary and epiclastic rocks. The Isle Galet Formation hosts several disseminated to thinly bedded Pb-Zn-Ag occurrences associated with altered felsic tuff and graphitic shale. They occasionally grade laterally into pyrite iron formation and appear to have been deposited in a very distal volcanic environment. The Isle Galet Formation is a time equivalent of the mineralized pre-Caradocian island-arc sequences of central Newfoundland, but differs from them both in style of volcanism and in the nature of the associated mineral deposits. It is, however, comparable in many respects to mineralized volcanic sequences in the La Poile Bay area of southwestern Newfoundland.Mineralization associated with granitoid rocks in Bay d&apos;Espoir is best developed around the southeast margin of the North Bay Granite, where two-mica leucogranite forms a marginal phase. Numerous minor base metal showings occupy quartz, quartz-carbonate and barite veins in the adjacent sedimentary rocks. Collectively, the showings exhibit a well-developed, zonal pattern around the granite margin; molybdenite (±py, cpy) predominates near the contact, giving way outward to galena (±sph, py, asp, cpy) and eventually to stibnite (±asp, py) at the periphery. Mineralization associated with granites in similar settings elsewhere in southern Newfoundland includes tungsten in the Grey River and Granite Lake areas and molybdenite in the Rencontre Lake area."

Jan 1, 1982

By F. P. Agterberg

"IntroductionTHE KNOWLEDGE about the mineral resources in a region ranges from relatively precise ore-reserve estimates for known deposits to probabilistic estimates concerning the speculative resources which may be discovered in future at greater depths and in the less-explored parts of the region. Previously developed probabilistic methods for regional resource evaluation (1) are based on the following two assumptions.(1) The probability that a specific block of rock, or part of a region close to the topographic surface, contains undiscovered deposits can be estimate d by weighting selected geological, geophysical or geochemical parameters for that block. The weights are computed by considering similar environments which are known to contain deposits.(2) Some of the characteristics of the undiscovered deposits, such as ore tonnages and average grades of metals contained in the ore, can be evaluated by considering probability distributions f or known deposit data. These methods were initially applied to Precambrian deposits in the Abitibi Volcanic Belt of the Canadian Shield (1).Since 1972, statistical methods for quantitative resource evaluation have been applied to the occurrences of the mainly Paleozoic base metal deposits in t he Canadian Appalachian Region. The objectives of this project (Project Appalachia) have been discussed by Leech (2) in a paper that introduces 8 papers with results of the exploratory data analysis. Project Appalachia represents an effort to develop and apply methods of combining information and concepts from regional geology, metallogeny and geomathematics for computer- aided regional mineral resource evaluation."

Jan 1, 1977

By R. Heikkilä

The utilization of Building Information Modeling (BIM) and model based 3-D control of work machines have increased a lot in new road construction in Finland as well as in other Nordic Countries. Up today, much less attention has been paid into the development of maintenance and rehabilitation processes. As a part of a large research and development program RYM PRE Infra FIN BIM in Finland, a focused research project of the BIM with experiments in total five (5) pilot projects has been performed. A main idea of the new BIM based process has been to utilize mobile laser scanning method for initial data acquirement, the use of novel 3-D analyze and modelling methods for point cloud processing, the use of new type optimization method for the planning of geometric and structural improvements needed for the existing uneven road surfaces, and further, through the creation of 3-D machine control models apply the newest 3- D machine control systems for continuous 3-D control of practical construction work using milling machine and asphalt paver. Finally, an evaluation is made between the new process model and the traditional way of working.

Aug 1, 2013

By E. J. Debicki

"At the 1992 PDAC Convention, Norman Keevil announced the formation of the Exploration Technology Division (ETD) of the Mining Industry Technology Council of Canada (MITEC). It was evident that base metal reserves in Canada were declining and that the cost of discovering a deposit in Canada was increasing. Coordinated research to develop new exploration technologies was required to discover the next generation of ore-bodies. The ETD was formed in response.The mission of the ETD is to contribute to the survival, profit, and growth of the Canadian mining industry by improving the efficiency and effectiveness of mineral exploration through development of innovative technology by man-aging and coordinating applied cooperative research. In addition, it is the intent of the ETD to become the principal agency by which cooperative research funds are transferred to researchers from the mining industry. The division is industry driven, industry funded and industry managed.The ETD’s Three-Year Plan has focussed80% of its research funds toward two objectives, improving the efficiency of exploration for VMS deposits and establishing the parameters necessary to discover the next Hemlo deposit. The remaining 20% is allocated to other projects, with the current emphasis on geophysics.In 1995, corporate members total twenty-three major mining companies accounting for90% of the exploration expenditures in Canada. The ETD is currently managing ten cooperative research projects totalling $4.6million. Other projects, estimated at $1.6 mil-lion, are currently under development."

Jan 1, 1996

By Gonzalo Mato, Colin Godwin, G. Ditson

"The mid-Cretaceous Seagull batholith intruded Mississippian sedimentary and volcanic rocks and Jurassic(?) granitic and ultramafic rocks within the Omineca Crystalline Belt in the Yuk on Territory near the British Columbia boundary. Leucoerotic fluorine- and boron-rich granites of the batholith exhibit many textural variations from aplite to pegmatite, but are dominated by a coarse-grained seriate unit and a fine-grained porphyritic unit.Four distinctive tin vein occurrences within and near the batholith are described, the most interesting of which is the MC showing of quartz-calcite-chlorite-cassiterite veins in intensely fractured zones of sedimentary and volcanic rocks. Three other showings occur within the batholith:J) the EC showing of quartz-fluorite-cassiterite-sulphide veins with prominent muscovite-illite alteration;2) the DU showing of quartz-hematite-fluorite-sulphide- sulphide-cassiterite with considerable manganese staining and sericitic alteration; and3) the VAL showing of quartz-tourmaline-cassiterite-fluorite-arsenopyrite veins with little associated alteration.Most cassiterite occurrences are within easterly-trending, vertical structures and all occurrences are thought to represent parts of a single system. These mineralogical and physical variations are apparently related to the distance from the upper contact of the batholith.For the Seagull batholith, Rb-Sr isotopic data give a 100±1.4 Ma isochron age that is concordant with the K-Ar model age from biotite of 101±4 Ma. Initial Sr isotopic ratios for the batholith are high at 0.712, indicating an old, sialic crustal source for this pluton. This initial ratio is similar to values for granitic rocks associated with tungsten deposits in the Yukon Territory. The high initial ratio for Sr, the high Si02 content, the high s/I index, the presence of normative corundum. leucogranitic composition and associated lithophile-tungsten mineralization demonstrate that the Seagull batholith is probably an S-type granitic body. This factor is significant to regional exploration jar tin and tungsten in the Canadian Cordillera."

Jan 1, 1983

By D. Moronkeji, R. Maharidge, D. A. Curry, B. J. Davis, U. Prasad, J. Franquet

"Proper shale characterization is crucial in shale gas drilling, exploration, completion and production. Unlike porous sandstone and carbonate reservoirs, the challenge with shales comes from their micro- to nano-darcy permeability ranges and the anisotropy of their mechanical and hydraulic properties. Most porosity-dependent logs are not sensitive enough to capture the true behavior of shales. Consequently, mineralogy and other strength and stiffness-related properties must be determined to characterize magnitudes and variances in shale mechanical and flow properties. In addition, these properties must pass quality assurance/quality control (QA/QC) practices to give confidence in their use in subsequent log calibrations, during geomechanical modeling, or in fracture design models. This paper presents a technique to integrate shale properties that are measured by various methods, and a methodology to perform QA/QC on the data before application.Shale properties originate from various sources, including downhole and laboratory measurements. Physical samples for laboratory testing are usually limited to a few depths. Lab tests are often costly, and replicating in-situ conditions can be difficult or impossible. In addition, results frequently show wide scatter, reflecting inherent depth variability and lateral heterogeneity. Wireline logs provide nearcontinuous data, but rarely yield direct measurements of rock strength properties. Although geomechanical and fracture models use log data, calibrating it with reliable and previously verified lab-measured properties is important. This paper presents a process to perform QA/QC on lab-measured data using various crossplots.Ten mechanical, microstructural and physical properties are graphically displayed to visually characterize shale strength behavior in ambient and in-situ conditions, whether measured or modeled statically or dynamically. These properties are often sourced from different departments. The properties are integrated but are individually subject to the previously mentioned uncertainties. Pairs of property values are crossplotted and compared with correlations from the literature or previously established with qualified data from related formations. Conformance with these correlations gives confidence in the data, whereas outliers are flagged as questionable. Repeating the process with questionable data crossplotted against other parameters for the same depth highlights the property with the greatest uncertainty. The determination of its value is investigated to locate the source of the inconsistency and establish a more reliable value. Where this is not possible, the user has a rational basis for rejecting that property value."

Jan 1, 2015

By Megan Becker, Aubrey Mainza, Indigo Research Laboratories, Jenny Wiese, Gaynor Yorath, Lucy Little

Particle shape characterisation has an important role to play in mineral processing, to clarify effects of shape on rheology, equipment wear rates, comminution, classification, sizing and flotation. However in industry, shape characterisation is not routine, and the most commonly used shape descriptor in the field (circularity/ angularity/ sphericity) is not invariant. This study aims to investigate shape measurements for a fine particulate ore sample measured with different analytical devices. Two Automated Scanning Electron Microscopy devices with Energy Dispersive X-ray Spectrometry (FEI QEMSCAN® and Zeiss Mineralogic®), and a camera based image-sizer using dynamic image analysis (Retsch CAMSIZER® XT) were compared. Each device was used to analyse the shape characteristics of specific particles in both a coarse sample (–212/+150 µm) and a fine sample (-53 µm) of UG2 platinum ore. Circularity and Roundness frequency distributions obtained from the three devices were then compared. For selected individual particles, circularity showed higher variability than roundness, and the sample circularity distributions obtained by the three devices were completely different. It is clear that circularity data from different studies relying on different devices should not be compared on an absolute scale. The shape parameter roundness was found to be a more robust descriptor than circularity, and it can give a stronger indication of a particulate sample’s shape characteristics on an absolute scale. However, there were still significant differences in the roundness measurements obtained by the CAMSIZER XT and the two Auto-SEM devices, which was attributed to the dissimilar mechanisms of image capture.

Jan 1, 2016

By C. K. Wilton

"The Agnew Lake uranium deposits were discovered in 1953 following the discovery of the Elliot Lake deposits to the west. The original property was optioned to Kerr Addison Mines Limited who added additional claims by staking. Agnew Lake Mines Limited was incorporated in 1967 to develop the property and a shaft was sunk to 1040 metres and five levels developed before work was suspended due to low uranium prices at the end of1970.In 1974-75 the mine was dewatered and production started in 1977. By 1978 reserves were estimated at 10,000,000 tonnes averaging 0.35 kg. U10 , per tonne. Underground operations were terminated in 1980 although a uranium leaching operation was continued until early 1983.The deposits lie near the contact of Huronian metasediments with underlying Algoman granite. The sediments consist of arkose, conglomerate, argillite and quartzite with the uranium mineralogy mainly confined to oligomictic quartz pebble conglomerate. The higher uranium values are related to conglomerate with highest percentage of pebbles. The chief uranium minerals are uranothorite and monazite. It is of interest that the uranium thorium ratio differs appreciably from that of the Elliot Lake deposits. This fact along with the fact that the Elliot Lake sediments were deposited by paleocurrents from the northwest whereas the Agnew Lake sediments were deposited by paleocurrents from the northeast indicates widely separate sources for the deposits. It is suggested that the Agnew Lake uranium deposits are syngenetic placers deposited under anoxygenic atmospheric conditions."

Jan 1, 1986

By K. B. Chaudhuri, I. D. Webb, F. E. Rachor, F. A. Sauert

"A characteristic of all methods of copper concentrate smelting is that slags with a high copper content are produced at some phase of the operation. Recirculation to the smelting unit, electric furnace reduction or flotation are at present used on an industrial scale to recover the copper from these slags. This paper describes the application of the top-blowing technique, originally developed by KHD Humboldt- Wedag AG for refining of metallic copper, for the treatment of copper-containing slags. By this method, a mixture of a reducing gas and commercial oxygen is blown onto the melt at velocities which can be supersonic from the tip of a water cooled lance. The impingement of the reaction gas mixture on the surface of the slag forms a depression in the molten phase and a deflection of the jet which brings the slag into a rotating motion. This causes high rates of heat and mass transfer. Results of pilot-plant tests for batch and continuous treatment of slags are presented, and the potential applications of top blowing for industrial-scale operation are indicated. In combination with the cyclone as a smelting unit, this process appears to be economic for smelters of very low capacity."

Jan 1, 1980

By R. M. de Carvalho

Empirical and phenomenological models of SAG and AG mills have dominated the scene for the last few decades, being used nearly every time a mill is scale-up or an attempt is made to improve its performance. However, in spite of their success, these models fail to describe the details of both the grinding environment and the breakage mechanisms. The result is a generally good track record, with a few – but very important – instances when these models fall short in their predictions, which can be very costly. Further, nearly all of these models require detailed calibration to industrial and pilot plant data, being costly in their application, although still with limited predictive capabilities. Recognizing these challenges, a new model framework has been proposed which overcomes the limitations of currently used models by coupling the microscale population balance model, the discrete element model and functions that describe internal classification at the mill grate. This model framework has already been applied to describe breakage in ball mills, with showing very promising results. However, in the case of SAG and AG mills a much greater level of complexity is involved in the model, given the interaction between the mechanical environment that is formed totally or, in part, by the ore itself, and the breakage response in the mill. The paper describes the model framework, demonstrating how it can address appropriately effects such as mill speed, mill filling and size distribution, on the response from the mill. Some of the advantages of the model are related to its intrinsic multi-component and dynamic nature, which allows simulating appropriately mixtures of ores of different competences in a transient manner.

Jan 1, 2012

By William Hawker, James Vaughan, Jeff Chen, Antony van der Ent

"Nickel agromining utilizes hyperaccumulator plants (“metal crops”) to extract nickel from low-grade soils, a process that yields high-grade nickel bio-ore. This feedstock is further processed into a range of nickel products. The bio-ore is relatively free of impurities that complicate the traditional processing of laterite nickel ores. In this paper, current primary nickel processing routes and proposed nickel bio-ore processing options are summarised. A novel pyro-hydrometallurgical route demonstrated at the laboratory scale is described. This process produces a precipitated nickel hydroxide product and takes advantage of the water-soluble basic compounds in the ash to minimise reagent requirements, thereby making it suitable for small-scale implementation in close proximity to the nickel farm. In this process, nickel is precipitated from the leach solution using the basic ash wash liquor. Leaching nickel from ash generated from open air burning requires strong acid and long residence times to obtain high recoveries due to its complex nature and distribution of nickel in multiple phases. This process can be improved by optimising the ashing process with respect to nickel leachability.INTRODUCTIONHyperaccumulator plants have the unique capacity to ‘biopurify’ and concentrate certain trace elements (e.g. nickel) from the soil into their biomass (Reeves 2003; van der Ent et al., 2015). Cultivating these plants as ‘metal crops’ by periodically harvesting and incinerating their biomass generates a high-grade bio-ore (Chaney et al. 1998; Li et al. 2003). This process is called phytomining or ‘agromining’ which is an emerging technology for extracting nickel from sub-economic resources (van der Ent et al., 2015). Potential near-term applications of the technology include implementation on land ahead of processing of the underlying ore-body (Willis 2015), as a mine-site rehabilitation strategy or as an alternative crop for farmers on land that is not suitable for normal food crops. In the longer term, nickel agromining could provide a significant supplement to the nickel supply chain. Critical to the success of agromining is effective bio-ore processing. Due to the unique chemical composition of this feedstock material, existing processes are not very efficient. Our current research efforts aim to develop new process options that overcome limitations of previously trialled routes. In this paper we summarise conventional nickel process routes and proposed new options for producing agromined nickel."

Jan 1, 2016