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By M. H. Dehghanpoor, M. Zivdar, M. Torabi

"A hydrometallurgical route was developed to extract metals such as gold, silver, copper, and selenium from anode slime from Sarcheshmeh Copper Complex in Iran. For the extraction of copper by leaching, the anode slime was heated and stirred with 4 M sulphuric acid in the presence of oxygen. Optimal conditions for recovery of copper were temperature 80°C, mixing time 5 hours, and oxygen flow rate 2 L/min, resulting in a copper recovery of 94.47%. Silver and selenium were dissolved by leaching anode slime from which the copper had been removed with nitric acid. For gold extraction, anode slime was heated with aqua regia at 90°, and the gold then extracted with 2-ethyl-hexanol at a concentration of 0.5 M and phase ratio of 4. The extract was then stripped with soda solution at pH=10.5 and a phase ratio of 5. Finally, gold was recovered by precipitation with oxalic acid at a ratio of mass to volume 10 g/L. Total gold recovery was 80%. IntroductionDuring the electrorefining of copper, some metals are accumulated in the byproduct anode slime, which is an important source for recycling and recovery of these metals (Petkova, 1994). In this paper, a hydrometallurgical route is described for the recovery of precious metals from copper anode slime of Sarcheshmeh Copper Complex, which is located in southeastern Iran .Copper anode slime is black or gray powder with a particle size less than 200 mesh. Approximately 2 to 20 kg of anode slime is produced per ton of copper cathode. The slime is characterized by higher amount of Ag, Se, Pb, and Cu compared to other metals and a very low Au content (Khaleghi and Ghader, 2013).The copper anode slimes are composed of 11.69% selenium, 3.93% copper, 5.26% silver, 0.13% gold, and 45% barite, plus lead, tellurium, antimony, sulphur, and silica with small amounts of nickel, iron, zinc, and bismuth. Gold is one of the most important noble metals due to its wide applications in industry and economic importance, so recovery of gold from slime is more appealing than that of other metals. According to the World Gold Council (2013), the demand for gold has increased during the last decade. This increase is due not only to the increasing demands of the jewellery market, but also to the increasing demand for gold in industrial as well as medical applications (Ranjbar et al., 2014)."

Jan 1, 2016

The proper understanding of the functioning of ground support under dynamic loading and the current approaches to designing of dynamic support are plagued by a great deal of uncertainty and lack of knowledge. This applies equally to the understanding of the support capacity as well as the demand placed onto the support due to dynamic loading. This lack of understanding currently leads to a case of design indeterminacy. This paper does not aim to solve this problem of design indeterminacy but to explore some of the issues that need consideration to obtain a better understanding of the dynamic demand on ground support systems. Keywords ground support, dynamic loading.

Dec 1, 2013

Excessive dust generation from unpaved mine haul roads is a problem common to most surface mining operations. While optimal road wearing course material selection parameters reduce the inherent dust generation potential, they do not totally eliminate fugitive dust. Many different classes of suppression or palliative treatments are available for mine haul roads and this paper initially ascertains basic selection guidelines, using a set of ideal dust palliative product, application and performance parameters based on mine road-user requirements. An evaluation and modelling methodology for truck generated fugitive dust emissions is developed as a basis for the comparative assessment of dust control strategies. For water-based spraying, a watering model was developed to estimate individual mine road watering frequencies for characteristic site parameter combinations during summer and winter operating conditions, for a required level of control or maximum dust defect. This forms the base-case scenario with which to compare the performance of other types of dust palliatives under the same conditions. Finally, a basic palliative economic evaluation model is introduced with the aim of identifying and costing the establishment, application and maintenance rejuvenation activities associated with the use of chemical palliatives. While palliative cost and performance is generally site specific, it is shown that under certain combinations of conditions, the use of dust palliatives has the potential to deliver cost savings when compared to water-based spraying.

Jan 1, 2007

By J. P. Gouvea

Back-analysis of two mining-induced tremors in 2011 was used to determine a modelling criterion for the entire Klerksdorp Goldfield (i.e., Vaal Reefs region). At that time, most mining operations in the region were owned by AngloGold Ashanti (AGA) and shared many geotechnical similarities. By 2018 AGA had sold off all its Klerksdorp operations to different mining companies, which continued applying the 2011 modelling criterion. As mining activities became more remote, scattered, and isolated, the extraction of isolated blocks of ground and remnants became increasingly necessary. However, the inherited criterion allowed only minimal or no mining activities at these areas. Keeping in mind that safety is the overriding consideration, an innovative numerical modelling approach, which includes the application of peak particle velocity designs, was developed to provide practitioners in the Klerksdorp Goldfield with a suitable criterion to justifiably and safely mine isolated blocks of ground and remnants. This would not always be possible if a conformist approach was used.

Mar 14, 2024

By M. Gao

The Zinifex Century Mine employs a large number of Detritor mills for fine and ultra-fine grinding to liberate silica and sphalerite at 80 per cent passing 7.5 microns before final zinc flotation. A joint project between CSIRO Minerals and the Zinifex Century Mine was carried out to evaluate the Detritor mill performance. Plant surveys were conducted around the Detritors in conjunction with laboratory tests. The survey data showed that the Detritors in the ultra-fine milling circuit performed well. They reduced a feed F80 sizing of 46 microns to a product P80 sizing of 7.5 microns at a gross energy consumption of 37.2 kWh/t. Scale-up of ultra-fine milling Detritors was studied using a 0.55 kW laboratory batch unit and a 355 kW full-scale Detritor by processing Century zinc concentrate with 1 mm sand media. The results indicated that the 0.55 kW laboratory mill underestimated the energy consumption of the full-scale Detritor by about 20 per cent for a product P80 of seven microns. The performances of a horizontal IsaMill and a vertical Detritor were compared as ultra-fine milling devices for processing Century zinc concentrate. The experimental data demonstrated that, when using the same grinding media, the energy efficiency of the two mills is similar despite the difference in mill designs. The Detritors used for regrind duty at the Century Mine performed poorly when processing feed at 80 per cent passing 88 micron. The energy consumption was high and the product size distribution was broad with particles above 100 microns in the feed unbroken and particles below ten microns overground. A coarser ceramic media of 3 mm was therefore tested in a laboratory Detritor to process the regrind Detritor feed as an alternative to the 1 mm Colorado sand used at the Century Mine. The ceramic media reduced the energy consumption significantly and produced a narrower product size distribution, which is more desirable for the downstream flotation process.

Jan 1, 2007

By and Z. S. Abisheva, Z. B. Karshigina, Ye. G. Bochevskay, A. S. Sharipova

The production of precipitated silica in the United States is about 145,000 tons of SiO2 and its prices vary significantly (from $ 1 to $ 4.5 per kg) depending on the area of its application. One of the most important parameters is its specific surface characterising dispersion (particle size and shape, presence or absence of pores), at a certain value of which the material acquires new properties and quality. At present, a technology has been developed for processing slag from phosphorus production to produce precipitated silica (‘white soot’) with a high specific surface and the possibility of extracting valuable components such as rare-earth metals (REMs) into a product enriched with them has been shown. However, the content of impurities in the deposited silicon dioxide, such as aluminum and iron, is above acceptable limits and may affect the quality of the final products. Therefore, along with the structure and specific surface, a very important characteristic of ‘white soot’ is the chemical purity of the material. In turn, calcium oxide occupies a significant share in the concentrate of rare-earth metals, which affects the content of ΣREMs oxides, which does not exceed 17.3 %. The low content of a valuable component may affect the feasibility of further processing. For the most complete utilisation of phosphorus slag, the authors propose a method for their acid processing, which allows for minimising the conversion of impurities to finely divided silica and collective concentrate, which will improve the quality of these products. Keywords: Phosphorus slag, precipitated silicon dioxide, rare earth metals, leaching, white soot, specific surface, technology

Jan 1, 2020

By F. H. Deist, M. P. Roberts

"The Collieries Research Laboratory of the Chamber of Mines of South Africa is developing a coherent system of programs to aid in the full spectrum of activities arising in the planning of new as well as operating mining enterprises. It is the purpose of this paper to describe the design and application of two subsystems in the complex.One of these subsystems is an initial version of a production simulator. This program draws upon a model of a mining enterprise and simulates the operational and financial aspects of a set of alternative mine production plans.These plans are specified in terms of proposed sequences of operations. Details such as reserves, production rates, resource requirements and so on, are taken from the model.Physically, the model takes the form of a cross-referenced data base, maintained by means of a general file maintenance system which is another subsystem described.The paper concludes with a description and analysis of the first practical application of the two programs."

Jan 1, 2014

By L. Thomas, A. Argyn, B. Mbao, G. Longo Banza

Since the first application of solvent extraction as part of the hydrometallurgical processing of copper, several studies have been carried out to optimize extractant formulations. In 2006, Solvay developed the ACORGA® OPT series of solvent-extraction reagents to optimize copper transfer by use of a blended formulation containing both aldoxime and ketoxime as well as selected modifiers. The incorporation of selected modifiers in these blended reagents resulted in increased copper transfer, due to the interaction between the modifier and oximes within the blend. By changing the ketoxime concentration and ratio of modifier to aldoxime, the strength of the formulation was optimized to enhance copper transfer and improve Cu:Fe selectivity. This formulation is well known in the African region under the ACORGA® OPT5540 name and provides the best performance at the conditions of agitated leach plants with pregnant leach solutions that fluctuate in Cu grade and pH. This paper discusses advantages of using ACORGA® OPT5540 in the Copperbelt

Jan 1, 2023

By M. Grave

Rock Engineers are required to design safe cost effective support systems and stoping layouts for their respective mines. As each stope has its own unique environment, continual re evaluation is required in all stopes to maximize extraction and achieve value from the support standard. This paper presents numerical modelling used to plan early mining within the shaft pillar and a reevaluation of an existing stope support standard.

Jan 1, 2009

By E. D. Musin, S. S. Gudkov, A. V. Epiforov, S. V. Balikov

The standard technology for processing of gold-bearing sulfide raw material has many problems associated with the use of cyanide as a gold lixiviant. Therefore, many tests to find alternative gold recovery methods are being undertaken. This paper describes some technological solutions, which can become alternatives to cyanide technology in the future. Pressure oxidation (POX) of refractory gold-bearing sulfide concentrates from five different Russian gold deposits were investigated. Concentrate 1 was gold-copper concentrate. Concentrate 2 was gold-pyrite concentrate. Concentrates 3-5 were pyrite-arsenopyrite double refractory concentrates. The POX tests were at temperatures of 110, 200 and 220 °C and oxygen pressures of 1.5, 2.4 and 3.0 MPa were carried out. Gold lixiviants, such as chloride, thiosulfate, sulfite and thiocyanate were tested. The recovery of gold from sulfide gold-bearing concentrates by non-cyanide methods was 97- 99%, and from double refractory concentrates, 86-93%. The tested reagents are less toxic than cyanide, and their use will reduce of the cost of gold production. These methods make it possible to recover gold in acidic media, and eliminate the washing operation and POX slurry neutralisation. In addition, precious metals recovery from POX cakes using lead reduction smelting was investigated. It was shown that the “POX-pyrometallurgical” technology for double refractory concentrates processing could be used with recoveries of gold and silver of 97 and 96%, respectively. Keywords: Recovery of gold, refractory sulfide gold-bearing concentrates, double refractory concentrates, pressure oxidation, non-cyanide lixiviants of gold, chloride autoclave leaching, thiosulfate leaching, thiocyanate leaching, sulfite leaching, reduction smelting, POX-pyrometallurgical technology

Jan 1, 2020

By R. Xie, J. Liu, Y. Zhu, Y. Li

The surface chemistry features of spodumene and feldspar were investigated by XPS, zeta potential measurements and first principle calculation. The results indicated that the zeta potential of feldspar was more negative than that of spodumene. The most possible active sites on spodumene and feldspar were Al sites and O sites. However, the number, type and activity of these sites were different. The flotation behaviour of five new collectors (cationic collector decyloxy-propyl-amine (DPA), anionic collector α-bromododecanoic acid (α-BDDA), N-Dodecyliminodiacetic acid (DIDA), and mixed collector DPA-BDDA and DPA-DIDA) were investigated through micro flotation experiments and analysed based on the surface chemistry features of spodumene and feldspar. The results revealed that cationic collector DPA processed a high collecting capacity for both minerals. The highest recovery of spodumene and feldspar was 91.60% and 95.30% respectively. The anionic collector α-BDDA and DIDA showed poor flotation behaviour. The recovery of spodumene and feldspar when using α-BDDA as collector was less than 5% and when using DIDA as collector was less than 1%. For the mixed collector DPA-BDDA, the recovery of spodumene and feldspar was 82.27% and 32.61% respectively at pH 4.5. For mixed collector DPA-DIDA, the recovery of spodumene and feldspar was 35.69% and 9.08% respectively at pH 5.8. The results indicated that the cationic collector had high collecting capacity, but low selectivity. The collecting capacity of anionic collector for spodumene and feldspar was poor at the same concentration compared with cationic collectors. Mixed collector DPA-BDDA showed good flotation behaviour and selectivity on spodumene. The ―COO- in mixed collector might improve the selectivity. However, too much ―COO- would increase the electrostatic repulsion, which might cause low selectively and poor recovery. Keywords: Spodumene, feldspar, surface chemistry features, mixed collector, flotation

Jan 1, 2020

By M. B. Cortie

An account is given of the development of ferritic stainless steels since their discovery in the early years of this century. The alloys became very widely used in the 1950s, the market during that decade being driven strongly by a demand for automobile trim made of ferritic stainless steel. The production of ferritic stainless steel declined as a proportion of the total at the end of the 1950s as consumer preferences changed. However, the market is now growing strongly again, this time driven by a demand for oxidation-resistant alloys for motor-vehicle exhaust systems. The tonnages produced, applications, and market shares of the various alloys are discussed and compared. Trends in world stainless-steel production, product forms, technological development, and usage are examined.

Jan 1, 1993

Production caving started for Lift 2 at Northparkes in August 2004. In a period of less than 3 months, more than 10 000 seismic events were recorded. Events up to local magnitude +2.9 were induced near the mine during caving, with event rates of up to 500 per day. This paper documents the seismicity related to cave initiation and cave propagation during the initial production of Lift 2. The seismogenic zone of events initially moved at a rate of about 0.5 metres per day, accelerating to 2 to 3 metres per day after a few months of cave production. Seismic data analysis infers that the crown pillar between Lift 1 and Lift 2 was destressed over a vertical height of about 100 metres. As the seismogenic zone approached the crown pillar, a macroseismic episode occurred, with more than 20 events of at least local magnitude +1 occurring in a two-week period. Based on the seismicity recorded for Lift 2 at Northparkes Mines, a caving mechanics model is proposed. Comments and suggestions are made for seismic data analysis and design of seismic monitoring systems in block caving mines.

Jan 1, 2008

By I. Cerny, M. Vanek, J. Hubácek

"SWOT analyses and the closely related TOWS matrix are frequent starting points for an organization to develop its strategy. The paper deals with the evaluation of the TOWS matrix and presents three novel approaches to evaluate the different factors of the TOWS matrix, namely (1) approach to evaluate the factors with identical weights; (2) approach to evaluate factors with their weights determined within the different quadrants of the TOWS matrix; and (3) approach to evaluate factors with weights determined within the whole TOWS matrix. The third approach has two variants. The proposed approaches to evaluate the TOWS matrix were tested on a SWOT analysis of a significant mining company in the Czech Republic. The results imply that the strategy W-T (weaknesses-threats) is recommended in three cases, while the strategy S-T (strengths-threats) is recommended once. The paper may be valuable for managers responsible for strategic planning.IntroductionThe process of human needs gratification has been closely connected with raw material resources of the planet. In the contemporary socio-economic conditions, the task of the mining company managers, apart from extracting mineral resources, is to meet the owners' intents.The managerial work itself becomes very complex. In mining companies in particular, the complexity is augmented by the characteristics of the business. Undoubtedly, the key factor is that mineral resources cannot be renewed or relocated. Stojanovi (2013) characterizes mining projects as involving great investments in finance and time, as well as consecutive decisions and a 'complex mosaic of numerous unknown factors that affect the value of the project'. He adds that mining projects are typified by a 'number of geological, technological, technical, economic, environmental, social, and financial risks' (Stojanovi , 2013).Inter alia, the managerial work may also be intese due to the dynamic internal and external conditions for the existence of any company (Vane? k, 2014). This tallies with Peter Drucker’s prediction in 1969; that the times at the turn of the millennium could be expected to be turbulent (Drucker, 1969)."

Dec 1, 2018

By R. D. Alorro, B. Tadesse, E. Aghaei

Cinnabar (HgS) and native mercury (Hg) are the most common naturally occurring forms of mercury found in most gold ores subsequently released into the environment during processing. Mercury and its compounds are extremely toxic and recognised as serious health and environmental hazards. This research investigates the possibility of mercury (Hg) removal from waste solutions from gold processing using iron-aluminium (Fe-Al) bimetallic particles. The synthesis of Fe-Al bimetallic particles using zero-valent aluminium and ferric chloride as precursors were performed following the optimisation of influencing factors. The presence of both metals in the prepared bimetals was confirmed by XRD analysis. The experiments for mercury removal by bimetals were designed using the central composite design and Minitab software based on two variables including contact time and adsorbent dosage. The best result of Hg(II) removal (>90%) was achieved using 4 g/L bimetals and contact time of 75 min. However, the statistical analysis of results indicated that these parameters have only a minor contribution to the removal of Hg(II) by Fe-Al bimetals. Higher bimetal dosage and contact time resulted in a higher Fe dissolution from the Al surface which can be attributed to the presence of nitrate (# $) ions in the solution. However, adding 0.1 M NaCl to the Hg solution had a positive impact on Hg removal by improving the conductivity and electron transfer within the solution. The Fe-Al bimetallic particles are promising substances for further testing of Hg removal from gold processing waste solutions with different conditions and constituents. Keywords: Mercury removal, gold processing, Fe-Al bimetals, optimisation

Jan 1, 2020

By Ron Tluczek

[Power Point Presentation]

Jan 1, 2006

By N. F. Dawson

Recovery of a chromite concentrate from UG2 flotation tailings streams, of a grade suitable for further pyrometallurgical treatment for the production of ferrochrome, has certain specific challenges not only by virtue of the decoupled nature of the primary PGM recovery process and secondary gravity based chromite recovery circuits, but also because of intrinsic variations in the nature of the ore and its mineral composition. Variability in the ore, together with upstream process dynamics, creates a challenging environment in which to achieve optimal recovery of a gravity concentrate with accurate grade control. This paper examines certain inter-relational aspects between the ore gangue and chromite mineral types, the influence of the primary PGM extraction circuit and secondary chromite extraction activity as applied specifically to UG2 ore against a background of actual plant experiences and circuit configurations applied in order achieve a suitable quality of chromite concentrate.

Jan 1, 2010

By J. Petersen, H. Naderi, M. H. Nikzad, M. Karimi

In this research, the thermodynamic study of sodium persulfate (Na2S2O8) solution in the presence and absence of H2SO4 and Fe3(SO4)3 was done. Eh-pH and equilibrium distribution diagrams were constructed using Outotec HSC Chemistry Software and the main stable ionic species were determined. Also, the mean activity coefficient and Pitzer model coefficients were evaluated. Effects of system composition, sodium persulfate concentration and temperature were investigated. According to the results, HS2O7 -, HS2O8 -, S5O3 2-, S4O3 2-, S3O3 2-, HS- and NaSO4 - are the main stable species in these three systems. Increasing of sodium persulfate concentration resulted in disappearing of SO4 2- and the appearance of NaSO4 -. The main effect of increasing the temperature from 25 to 75oC, is changing the stability regions of HS2O7 -, NaSO4 -, SO4 2- and S2-. From equilibrium studies, it was concluded that at 25 and 50oC, increasing the persulfate concentration results in a 55-60% decrease for HS2O7 - and an 20- 30% increase for HS2O8 -. At 75oC, HS2O8 - becomes the main species and its percentage decreases with increasing the persulfate concentration. Keywords: Thermodynamic, sodium persulfate, activity coefficient

Jan 1, 2020

"The management of outlier grades in positively skewed gold distributions is a contentious issue. Incorporating outliers in standard ordinary kriging (OK) estimation procedures in a way that honours the data without smearing extreme grades into surrounding areas has been problematic. Cutting or capping of outliers to mitigate their influence in estimation techniques is common practice, while methods that manipulate the OK system of equations fail to honour the data. We propose a method of post-processing of kriging weights that provides realistic OK estimates and mitigates smearing without manipulating kriging equations or changing the original grades. The method requires that the data is not clustered, is approximately equally spaced, and is of the same support. Positively skewed data is ordered on attribute grade and nonlinearly transformed to a Gaussian histogram of categorical bins whose frequency is based on their likelihood of occurrence and location in the sample distributions. Factors that restrict kriging weights are calculated by dividing the percentage frequency of data in each bin by the percentage frequency of data in the bin with the highest frequency. Restriction factors applied to the kriging weights in the OK estimation restrict the range of influence in proportion to their probability of occurrence in the distribution. Smear reduction post-processing is easy to implement and addresses issues arising from negative kriging weights while considering the spatial location of samples, the sample grades, and their probability of occurrence. The method mitigates both smoothing and conditional bias.IntroductionOutliers are sample observations that deviate considerably from the standard or expected (Hawkins, 1980). These deviations can be high or low in grade depending on the distribution. The presence of outliers in a mine sampling campaign could provoke mixed reactions. Mining engineers might view high-grade outliers as a promise of achieving higher grades, while the geostatisticians view outliers as affecting the accuracy and precision of the overall estimate, among other issues. Having identified outliers, the geostatistician must decide how to account for their presence and treat them so that true underlying estimates are not distorted. Advanced knowledge of the deposit allows the geostatistician to identify and treat outliers acceptably, especially where samples are limited in number and the true grade distribution is uncertain. If ignored, or treated incorrectly, outliers are likely to lead to smearing of extreme grades into the surrounding estimates, thereby steering regions towards potential under- or over-estimation."

Apr 1, 2019

By P. O. Akinseye, F. T. Cawood

Mineral royalties are one of the oldest forms of mining taxation, and were initially introduced to extract economic rents from mining. Over time, the royalty regime has become more complex as it was identified as an important policy instrument that can achieve more multi-faceted outcomes. Such a multi-tiered approach in the use of the royalty instrument is also the case with South Africa. With South Africa’s new mineral royalty regime now in place for ten years, it is perhaps time to assess its impact and effectiveness. To carry out this assessment, an econometric evaluative study was undertaken using four major commodities in South Africa, namely gold, platinum, iron ore, and coal. The study explored five different policy options for government to consider and tested them to determine the most favourable one that will realize the regime’s policy objectives. After the assessment, two major options stood out. Hence, this paper seeks to highlight which of the two options is the most favourable for consideration by policymakers. Based on that study, we find that the current structure is effective, but also recommend that the factors in the formula for refined minerals be ‘modified’ to reduce the capped profitability ratio from the current 60% to 30% and the maximum royalty rate for refined minerals from 5% to 3%. The minimum rate of 0.5% during times of depressed mineral prices and no or low profitability will not be affected.

Dec 1, 2021