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By D. Moradkhani, S. M. Javad Koleini, M. Abdollahy, F. Soltani

"The objective of the study was to determine the type and distribution of rare earth elements (REEs) in the phosphate flotation concentrate from the Esfordi flotation plant in central Iran, in order to understand their leaching behaviour. Samples of the concentrate were prepared and analysed using XRF, XRD, ICP, and EMPA. The Ce, Nd, La, and Y contents were 5608, 2227, 1959, and 679.7 mg/kg, respectively. The main REEbearing minerals in the concentrate are fluorapatite, monazite, and xenotime. Apatite is the chief mineral of the concentrate and the ratio of apatite to monazite is greater than 60. From EMPA analysis, monazite contains a much higher proportion of REEs than apatite, but more than 50% of the REE content of the concentrate is in apatite, as this is the main mineral constituent of the concentrate. During the leaching of REEs in the phosphoric acid production process, more than 99% of the total rare earth values report to the large amounts of phosphogypsum (CaSO4·2H2O) formed during the dissolution reaction. Accordingly, two process options are suggested for treating the Esfordi concentrate. In the first option, the concentrate is treated with 98% H2SO4 at 200–300°C. After digestion and water leaching, phosphorus and REEs are precipitated out of solution. In the second option, the concentrate is treated in a pre-leach stage. The process residue from the pre-leach stage is then subjected to acid digestion at elevated temperature for phosphoric acid production.IntroductionThe rare earth elements (REEs) comprise a set of 17 chemical elements in the periodic table, specifically the 15 lanthanides plus scandium and yttrium. REEs and alloys that contain them are used in devices such as computer memory, rechargeable batteries, cell phones, catalytic converters, magnets, fluorescent lighting, and many more (Krishnamurthy and Gupta, 2004). China supplies about 94% of the REE demand, with the remaining 6% coming from Russia and Estonia, the USA, India, Malaysia, and Brazil (Zhanheng, 2011). Increased industrial development in China has prompted the Chinese government to limit annual export quotas to approximately 35 kt of rare earth oxides (REOs), while non-Chinese annual demand is expected to reach 80 kt by the year 2015. This constriction of supply is being met by the development of many new rare earth mining projects, each of which has its own unique mining and processing challenges (Jordens, Cheng, and Waters, 2013). One of these projects is the Esfordi phosphate project, which is located in Yazd Province in central Iran. The concentrate from the Esfordi flotation plant contains 1.2–1.5% REEs."

Jan 1, 2017

By M. Solomon

During the course of 2011 the nationalization of mines emerged as one of the most contentious and emotive political issues under review. Some four years after the African National Congress electoral conference held in Polokwane, which had led to a change of leadership within the country's ruling party, elements within the ruling party's youth league, which had been virulently supportive of the change in leadership, turned on the incumbent President, using the mining question as its rallying call. At issue was the expressed perception that mining has, since the country's democratization, not delivered the anticipated benefits to the population as a whole, continues to be the preserve of the capitalist element of the South African community, and is therefore in need of radical reform. Aspersions were made that transformation within the industry had failed dismally and that mining companies had not delivered against their commitments to the Mining Charter and social and labour plans. The debate became extremely vocal and heated, evoked dramatic and emotive opinions, and vigorous skirmishes on the matter were fought in the media over much of 2011 and into 2012.

Jan 1, 2013

By B. Gamble

Solid Energy's project evaluation process utilises a standard staged gate approach, with five levels leading ultimately to project execution (level 6). For a project to progress through each level, specific financial criteria need to be satisfied. Solid Energy primarily use value based (discounted cash flow) metrics to support investment decisions. Within this approach Solid Energy utilise a number risk-based techniques to quantify project uncertainty. This includes the use of risk-based probabilistic analysis using Monte Carlo simulation and probability-based scenario analysis. Figure 1 shows the net present value (NPV) cumulative probability. Project risks are identified through comprehensive risk workshops. The output of these workshops (list of key risks, ranges of uncertainty and probability of occurrence), is quantified within the financial models. Incorporating this risk information on a probabilistic basis allows an investment decision to be made with a robust knowledge of the range of possible project outcomes along with the likelihood (probability) of those outcomes occurring, for example 80 per cent confidence that the project value will be greater than NZ$10 M, 50 per cent confident it will be greater than NZ$50 M and ten per cent confident it will be greater than NZ$70 M. Incorporating risk implicitly into the financial analysis allows the business to easily evaluate/measure projects with different risk profiles. The detailed risk analysis does away with the complexity of arbitrary risk-based hurdle (discount) rates, as projects can be evaluated based on their specific risk characteristics. Whether a project will progress to the next level of investment and ultimately into implementation depends firstly on the value assessment in comparison with the associated risk/uncertainty, and secondly matching this with the businesses appetite for risk. At Solid Energy standard criteria are used for specific project evaluations, but in addition projects are considered on a portfolio or strategic basis also. Solid Energy attempts to maintain a mix of low risk (low value) projects with some high risk (high value) opportunities. The mix of projects must remain in line with the shareholders' risk appetite. One of the keys to a successful investment decision is ensuring that the appropriate information is available to decision-makers so that they may proceed with a comprehensive understanding of the risks and impacts associated with the decision.

Jan 1, 2007

By C. Yu, N. Topliffe, H. Song, W. Yu

The water separation pump is a highly effective alternative for medium pressure (1.6?6.4 MPa) slurry pumping requirements and has been widely used in industry since it was invented in the 1980s. The water separation pump is powered by a single or multi-stage clean water centrifugal pump. The water separation pump combines the advantage of high flow centrifugal pumps with the high pressure capability of reciprocating pumps. The clean water pressure is exchanged to slurry kinetic energy through the separating chamber, the principle component of the water diaphragm pump. Currently in its the third generation, the separation chamber uses a ball and flexible water seat that provides a true separation mechanism and can completely isolate the two fluids with near zero water loss.

Jan 1, 2007

In Chapter 1 we mentioned that up to three components are considered to represent the variability of regionalized variables : a deterministic component, a correlated component, and a random component. In Chapter 2 we considered some of the models based on the assumption of randomly distributed values: the random component was assumed to be the only one present. In Chapters 3 to 11, more general but also more complex models were described, based on the assumption that the values were correlated with the possible presence of random noise. In this chapter we introduce a model used to analyse non- stationary data, for which a deterministic component (or drift) must be assumed. This model will be used for estimation purposes, and the corresponding optimal linear estimation procedure is known as universal kriging. The theory of universal kriging is much more complex than the theory of kriging. Fortunately, in the majority of mine valuation problems the drift can be ignored and the simpler form of kriging can be used.

Jan 1, 1978

By K. Bryan, O&apos

A 10-year program to integrate crushing and screening models into daily flowsheet design practice has proven successful. A Circuit Analysis Program (CAP) is used worldwide to design and evaluate new and existing crushing flowsheets. To gain user acceptance of CAP and maximize effectiveness, model development, simulation flexibility, ease of use, and developing international access are key issues. These issues have been resolved effectively resulting in flowsheet simulations to assist in justifying increased capital investment. CAP is presently utilized in Canada, United States, and South Africa with intentions to expand to Europe and Asia.

Jan 1, 1987

By D. Seke

Metal inventories are usually reported in financial statements of mining companies. However, the value of these inventories can be reliable only if the metals in stock are measured within acceptable tolerances. Reliable metal balancing requires accurate mass measurement, sampling, and chemical analysis. Many mining companies are usually unable to validate the accuracy of metals in inventories at the end of their financial year. This is mainly due to poor mass measurement, sampling, and chemical analysis practices. This has an adverse impact on metallurgical accounting and metal valuation. In addition, it puts a lot of stress on external auditors, who have the duty to recommend the approval of the financial statements to the board of directors. Although a full value chain of metal reconciliation includes the accuracy of Mineral Reserve definition and grade control at the mine, this paper discusses the implementation of best practices for mass measurement, sampling, and chemical analysis at processing plants. This is an important aspect of sampling and reconciliation that is required in order to improve the reporting of inventories in the financial statements of public mining companies. Keywords metallurgical accounting, corporate governance, sampling, analysis.

Jan 1, 2014

By C. Chongo, F. X. Paquot, C. Ngulube

"Over the last six years, the Kansanshi copper-gold mine has continued to process significant quantities of complex transitional mixed ores. Initially, the ore treated came predominantly from accumulated stockpiles. Subsequently, the feed source shifted primarily to freshly mined ore that generally showed less tarnish with better flotation kinetics, but with the downside of lower concentrate grades. A number of changes were made to improve the efficiency of the rougher circuit and quality of concentrate produced. These changes were as a result of initial mineralogical studies and laboratory flotation test work that were discussed at length in a previous paper1. Salient among the recommendations adopted as a result of previous work were increased circuit capacity and a modified configuration to increase the residence time and the number of sulphidization stages. These modifications were completed and commissioned in 2011. This, however, resulted in significantly low rougher concentrate grades and a below-specification final concentrate product. This was due primarily to higher mass pulls from the extended rougher bank with multiple concentrate discharge streams, and which necessitated an enlarged cleaning capability. The extra cleaning capacity came on stream in 2014. Of note was the development of a recovery model, based on the strong correlation between the total copper and acid-soluble copper ratio, as a tool for monitoring plant performance. IntroductionThe Kansanshi mine, the largest copper mine in Africa, is 80% owned by Kansanshi Mining plc, a subsidiary of First Quantum Minerals. The remaining 20% is owned by the state through the parastatal Zambia Consolidated Copper Mines Ltd (ZCCM). The mine is located approximately 10 km north of the town of Solwezi and 180 km to the northwest of the Copperbelt town of Chingola. The mine has been in commercial operation since 2005."

Jan 1, 2016

By B. P. Watson

The Bushveld platinum group metal deposits in South Africa are the largest in the world. These deposits occur as two distinct stratiform tabular ore bodies and strike for many hundreds of kilometres. Mining is extensive, with depths ranging from close-to-surface to 2300 m. The mining method is a variation of planar open stoping. Crush pillars are widely used to support the open stopes. These pillars are designed to fail and the residual strength provides the required support resistance to stabilize the stoping excavations. This paper describes the in situ measurement, of stress within a Merensky pillar from Impala Platinum. These measurements were used to derive a stress-strain curve that includes pre and post failure behaviour. 2D FLAC modelling, with strain softening, was done to investigate how damage expands into the hanging- and/or footwall. Although the so-called ?squat? effect is always present, the modelling suggests that it does not dominate the pillar system behaviour at larger width to height ratios. Punching of the pillar into the hanging- and/or footwall increasingly controls the pillar system behaviour with larger width to height ratios. The paper investigates the behaviour of a system that incorporates the immediate hanging- and footwall, as well as the pillar itself.

Jan 1, 2009

By R. G. B. Pickering

The Faculty of Engineering at the University of the Witwatersrand and the Mining Technology Division of the CSIR have co-operated to define the problems associated with deep level mining and in this paper they will identify what they consider to be the critical areas requiring technological solutions. This perspective will then be applied to work currently being carried out by both the organizations and gaps for additional developments will be identified. Finally the Co-operative Research Centre methodology operating in Australia is described. The purpose of this CRC is to provide a vehicle for R&D co-operation to develop and implement technologies which will increase the competitiveness of the mining industry. A further objective is to develop an appropriately skilled human resource base.

Jan 1, 1996

By P. J. Petit

The strategic mission of the South African mining industry is to extract the mineral assets in an energy efficient, economical and safe manner. Drilling has received particular attention in the last few years. As the operations move away from the power source, conventional and old drilling technology result in poor penetration rates, increased drilling shift lengths, slow face advances and limited stope efficiencies. The need for an alternate mining method, performed by a skilled workforce, to increase productivity, has led to the development of the electric rock drilling system for in-stope mining operations. The focus of this paper is a systematic evaluation of the electric rock drilling system as a function of production and technical parameters, in the platinum orebody. The particular electrical reticulation system is illustrated. Power usage, problems experienced, and solutions are described. The safe use of the recently developed drill is elaborated upon by describing protection devices. The testing and certification process, for approval by the recognized authorities, are documented. The testing and certification process, for approval by the recognized authorities, are documented. The human factor is also considered. Known detrimental factors of high noise exposure, vibrations levels and oil emissions are reviewed. In conclusion, recommendations on future strategies for the implementation of electric drilling technology within the mining and construction industries, is included.

Jan 1, 2006

Outotec?s direct leaching process is an atmospheric leaching process for sulphidic zinc concentrates. The direct leaching process, based on special leaching reactors developed by Outokumpu, is the most economical way to produce electrolytic zinc. The production scale applications of the process realized so far are in use at Boliden?s Kokkola and Odda zinc plants. A new full-scale application of Outotec?s direct leaching process will be started in 2008 in China. The process is integrated into the existing production plant, replacing part of the old production facilities by modern technology. Besides high zinc extraction the plant expansion and modernization offers also indium recovery, iron precipitation and solution purification processes. The process equipment includes tailor-made reactors designed on the basis of the work and experience of Outotec research centre. Keywords: zinc, concentrate, atmospheric leaching, technology, indium, iron precipitation, solution purification, Outotec.

Jan 1, 2008

By Daniel W. Kappes, Pierre F. X. Mousset-Jones

"In this paper a discussion is presented of a program designed to produce a 40-day production forecast for an underground stoping system.The program is intended to be a tool for the operations department in an underground mine, and is designed to utilize data readily available from production reports. Brevity of data input, ability to revise slope conditions easily and the accuracy of starting stope status are stressed. Applicability of the program to a wide variety of sloping methods makes the program potentially useful in a large number of mines.The general functions of the program subroutines, and input and output lists are discussed. An example is also given of a stope in operation for a three-day period, which shows how the program can handle production irregularities as they arise."

Jan 1, 2014

Nowadays, fully encapsulated rockbolts have become a key element in the design of ground control systems. The main reason is that they offer high axial resistance to bed separation. In this research, the load transfer capacity of a fully grouted bolt is evaluated analytically in an elastoplastic rock mass condition. The research considered the effect of bolt end-plate on load transfer capacity. Bolt and surrounding materials were assumed to be elastic and elastoplastic materials respectively. The load transfer mechanism of a fully grouted bolt is a function of parameters such as bolt length, shear stiffness of interfaces, in situ stress, presence of face-plate and distance along the bolt. These factors were analytically evaluated. Finally, the load along the bolt was predicted in different surrounding rock mass characteristics.

Jan 1, 2011

By S. Kirkpatrick, J. Mukendwa

"The mining operation at Namdeb’s Southern Coastal Mine (SCM) is unique. It targets gravel layers up to 30 m below sea level, which continue to dip deeper, further west, under the Atlantic Ocean. On this storm-dominated coastline, severe water seepage into mining areas, rugged orebody footwall characteristics, and highly variable resource grades all contribute to a challenging operational environment. Namdeb has a proud history of innovation, and as the mine progresses further westwards and associated technical and economic challenges increase, this innovative culture has become essential to the future of the mine. The Theory of Constraints (ToC) has been widely used at SCM, and across the mining discipline, to focus efforts on improving overall business profitability. Through analysis of the mining processes, opportunities were identified, solutions developed, and initiatives implemented with staggering results across all three mining disciplines, i.e. stripping, load and haul, and bedrock bulking and cleaning. This paper outlines the solutions adopted and the results of the ToC analysis. IntroductionSouthern Coastal Mine (SCM) is one of three Namdeb operations located in the southwestern corner of Namibia, between the Orange River in the south, the Namib Desert to the east and the Atlantic Ocean to the west (Figure 1). These three geographical features set the backdrop for the world’s greatest marine diamond mining placer (Badenhorst, 2003). SCM is situated along the coastline extending from the mouth of the Orange River to Chameis Bay approximately 120 km to the north. The active mining area, called Mining Area 1 (MA1) is, however, limited to very narrow strip, 30 km in length, in the south of the licence area, close to the town of Oranjemund.Namdeb, a wholly owned subsidiary of Namdeb Holdings, is a 50/50 joint venture between De Beers and the Government of Namibia. Diamonds were first discovered along the Namibian coastline in April 1908, close to the town of Luderitz, but mining operations started in the SCM mining area only in February 1929 (Schneider, 2009). Initially all Namdeb mining operations exploited massive land-based deposits, producing nearly 40 million carats from MA1 between 1920 and 1977 (Schneider, 2009) when mining targeted onshore raised beaches west of the high water line. Since 1977 however, SCM and Namdeb have developed a unique mining method to economically extract the resource which extends westward under the Atlantic Ocean."

Feb 1, 2019

By J. J. S. de Beer, F. Hunter, A. F. Neethling

SYNOPSIS The paper describes the rib-pillar extraction method now used at Sigma Colliery in the Orange Free State. In this method, access roadways (with a high safety factor) are developed into a block of coal suitable for total extraction; pillars that have a low safety factor are then formed and extracted immediately. The method, together with the current practices of labour management, has resulted in better utilization of the coal resources and capital, increased production and labour productivity, and improved safety.

Jan 1, 1991

By R. M. Lamya

A semi-empirical kinetic model was developed for the atmospheric leaching of a Ni-Cu matte in copper sulphate-sulphuric acid solution. Kinetics of the leaching process was studied as a function of initial copper ion concentration, initial acid concentration, temperature, stirring rate and particle size distribution. The kinetic model was developed on the basis of the leaching mechanism and chemical reactions of the leaching system investigated, and was evaluated by comparing the model predictions to experimental data. The model was found to satisfactorily fit the trends in the leaching of the metals, namely copper, nickel, cobalt and iron.

Jan 1, 2009

By F. Hees, A. H. Bracken, L. I. Boshoff

"Biological cementation of the Mandena heavy mineral sand deposit in Madagascar was causing difficulty in dredge mining and hence in planning and control of production rates. An investigation was initiated to better evaluate the geotechnical properties of the orebody by defining the distribution and geotechnical properties of the cemented strata, in order to generate a site-specific geotechnical model for the deposit. The geotechnical characterization was developed by an integrated approach using several ground investigation techniques such as piezocone (CPTu) testing, geotechnical drilling, standard penetration testing (SPT), as well as laboratory testing. The final outcomes of the investigation included a 3D geotechnical model showing the distribution and extent of the cemented areas, as well as the typical geotechnical parameter ranges associated with each of the defined geotechnical units. The interpretations developed were incorporated into the mine and production planning to ultimately optimize operational planning and control.IntroductionQIT Madagascar Minerals (QMM) is a heavy mineral sand mining operation at Mandena, near Fort Dauphin in Madagascar. During the final planning and commissioning stages of the project, the need to fully characterize the unusual geotechnical conditions was identified and a geotechnical investigation became necessary.Nature of the problemDuring the commissioning phase it was found that mining production was being hampered by biologically cemented/indurated layers encountered within the sands. Closer inspection of the indurated horizons in the dredging face revealed that these layers contain a high loading of bacteria and fungi. It appears that the bacteria produce an extracellular (outside the cell) polysaccharide (i.e. sugar and carbon salts), which form a gelling biofilm to trap nutrients. There are a number of different bacteria. The fungi, on the other hand, produce a network of fibrous strands that bind the sand grains together. Thus both bacteria and fungi probably contribute to the ‘apparent cohesive’ strength or binding of the indurated sand (Lynn, 2008)."

Jan 1, 2017

By R. P. H. Willis

This paper describes the economics of backfilling, hydro-power, and mechanization when they are combined in an integrated stoping system. These three technologies have been shown to be viable, and the mines of the Gold Fields Group are introducing backfilling where the depths exceed approximately 2000 m below surface and in other highly stressed areas. addition, a number of mines are installing hydro-powered systems, and the first trackless stope within the Group may soon be a reality. The main emphasis in the paper is placed on the quantifiable effects of trackless stoping, including a basic risk analysis by use of a spreadsheet model. It is concluded that a substantial decrease in working costs and an increase in revenue are possible, resulting in a marked increase in working profit.

Jan 1, 1989

In order to test the applicability of elastodynamic codes in the modeling of mining related problems, comparisons are made between seismic data and numerical analyses. The dynamic finite difference program WA VE is used for the modeling of a horizontal stope in a deep mine. The slip along a vertical fault situated within the positive excess shear stress lobe of the stope initiates seismic waves. The stope-fault geometry is modeled in both two and three dimensions. The three dimensional non-slip weakening WAVE analyses correlate well with Brune's analytical model. For accurate modeling of the peak particle velocities predicted by McGarr's empirical relationship, it is recommended that a three-dimensional stope -fault model is used, with the amount of slip weakening dependent on the magnitude of the event.

Jan 1, 1995