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By G. S. Hansford, G. E. Searby

"Ferrous iron oxidation kinetics was measured in continuous culture at temperatures between 65 and 75ºC, using thermophilic microbes suitable for high temperature bioleaching. The resulting specific oxidation rates were modelled as a function of the ferric/ferrous iron ratio. The results were compared to those obtained by conventional mesophilic microbes.Microbially mediated ferrous iron oxidation is a vital sub-process in the mesophilic bioleaching of sulfide minerals and is expected to be of similar importance at elevated temperatures using thermophilicmicrobes.A thermophilic archaeal culture used in chalcopyrite bioleaching was successfully grown in continuous culture on ferrous sulfate, indicating the capability of the microbes to sustain growth for long periods on the energy provided by the conversion of ferrous iron to ferric iron, the primary leaching agent in sulfide mineral bioleaching.Steady state data was obtained at residence times of between 70 and 10 hours, with washout occurring at residence times between 11 and 9 hours, corresponding to a maximum growth rate (µmax) of between 0.09 and 0.11 hr-1. The reactions were followed by measurements of the solution redox potential, soluble iron concentrations, and offgas analysis of the oxygen and carbon dioxide utilisation rates."

Jan 1, 2003

Results of the study of chloride ion concentration effect to osmium-187 sorption from wastewater of copper smelter with use of foreign anionites of different basicity and structure are presented in the work. It was found that the increase of chloride ion concentration in the wastewater helps to increase recovery of osmium using anionites regardless of their nature. The ways to intensify the process are proposed. The method for osmium elution from the anionites with potassium iodate solution was developed. It was shown that the method lets to recover up to 99% of osmium from the anionites. Recommendations for selection of eluents for better recovery of osmium from the anionites were elaborated. Keywords: wastewater, osmium, anionite, sorption, chloride ions, eluent, recovery

Sep 1, 2012

By J. D. Miller

The more efficient production and use of mineral resources is a major objective of our sustainability efforts. Resource characterization is a critical component for optimization of the mine-to-mill process, including innovative processing for sustainable growth. Such characterization is now referred to as geometallurgy, with advanced instrumentation including, for example, particle size analysis, XRF, XRD, NIR, automated SEM/EDAX analysis (QEMSCAN, MLA), and high resolution X-ray micro tomography. Geometallurgical information is important for exploration, deposit evaluation; mine planning, design and analysis of separation processes, etc. Characterization of mineral processing particles in 3D is now possible using high resolution X-ray micro tomography (HRXMT), and such HRXMT systems have been installed at several laboratories around the world. After review of principles, the features of such HRXMT analyses are presented including size/shape, damage state, mineral phase identification, and evaluation/isolation of trace mineral particles. With new algorithms for image analysis, quantitative data treatment is possible for construction of liberation-limited grade/recovery curves, for the determination of specific crack surface area, and for complex texture analysis including grain exposure. Finally, new tomographic characterization possibilities are discussed to provide the foundation for the development of advanced, innovative processing strategies for sustainable growth. Keywords: X-ray tomography, resource characterization, HRXMT, particle size analysis XXVI INTERNATIONAL

Sep 1, 2012

By D. Chakraborty, Neeraj Kumar

"The study provides the comparative analysis of the performance of water only cyclones and hydrocyclone for iron ore fines processing at Joda Iron ore processing plant, Tata Steel. Joda iron ore deposits have higher proportion of kaolinite in the finer fractions and are meant to be separated with cyclones. The iron processing flowsheet of Joda comprises of water only cyclone for beneficiation of iron ore fines. Water only cyclones are used for the beneficiation of fines in the iron ore processing industry and have a larger cone angle compared to that of conventional hydrocyclones to enhance the density effect in the separation. They are aimed to achieve better product quality of underflow however; the desired result could not be achieved at the Joda processing plant. The water only cyclones were operating at the corrected cut-size of about 60 micron with an imperfection of 0.40 and water split to underflow was approximately 10%. The overall Fe recovery from the water only cyclones were 60%. Since the quality of fines produced from the water only cyclone couldn’t be improved, an attempt was made to process the fraction in the conventional hydrocyclone to achieve the desired product quality. The trial results indicated better product quality with the Fe recovery of 72% at corrected cut-size of 70 microns and imperfection of around 0.29. In view of above results it was recommended to replace the water only cyclones with hydrocyclones to achieve higher product quality of about 60% Fe content.INTRODUCTION Water only cyclones were installed at wet plant, Joda to process the classifier fines where the cyclone underflow is considered as concentrate and overflow is discarded as slime. Because of the lower capacity of the cyclones 30% of the classifier overflow was bypassed directly to thickener. Apart from this the quality of fines produced from the water only cyclone couldn’t be improved further hence an attempt was made to process the fraction in the conventional hydrocyclone to achieve the desired product quality and quantity. Hydrocyclone was installed at Joda after replacing stub-cyclone and came into operation on 23rd Aug’ 2017.The process variables of water only cyclones and hydrocyclones are tabulated below:"

Jan 1, 2018

By Jeremy Bosman, Niel Lourens

"Cyclones are used in four main applications in primary wet heavy mineral processing plants i.e. upfront desliming, densifying, and concentrate stacking and tails deposition.UPFRONT DESLIMINGMany heavy mineral ore bodies are associated with high slimes varying from 15 to 60%. The increased viscosities arising from the slimes impact negatively on heavy mineral recovery in the spiral plant. Recoveries can be reduced by up to 10%. Cyclones have proven to be able to remove slime efficiently with acceptable loss of valuable heavy mineral in the overflow. For low slime applications, typically below 25%, it is possible to achieve the desired results using a single stage of cyclones, whilst for higher slimes, two stages of cyclones are required. The overflow of the primary stage is retreated through a second stage to minimize heavy mineral loss."

Jan 1, 2003

By M. M. Bugarin, P. J. van Staden, V. T. Conic, S. S. Dragulovic, R. M. Kovacevic, D. B. Milanovic

"The mineralogical and physico-chemical characteristics of a polymetallic sample from a mine of West Serbia suggest that it can be classified as a SEDEX type of ore. Those ores contain multiple value components, being inter-dispersed as fine grained aggregates. This prevents concentration by gravity or flotation concentration processes. Mineralogically, the valuable metals (Cu;Zn;Pb;Au and Ag) occur as pyrite, sphalerite, galena, tetrahedrite, chalcopyrite, covellite, arsenopyrite, and non-metallic minerals (barite, and waste minerals). Novel technologies are under development within this project for the recovery of all valuable metals from this very complex material. The work comprises the further treatment of solid residue obtained after Cu and Zn extraction by bioleaching, for the subsequent recovery of Pb and the precious metals Ag and Au. The residue is first treated with a saturated sodium chloride solution, whereupon a chloride solution of lead (NaPbCl3) is obtained. From the chloride solution, lead was deposited in the form of lead carbonate, followed by reductive melting, whereupon lead anode was obtained. Electrolytic refining of the lead anode, using a solution of PbCO3 in methane sulphonic acid (MSA-Methanesulfonic acid, min 99.5% CH4O3S, density 1.48 kg/dm3, Manufacturer: Carl Roth) as an electrolyte, yielded refined lead cathode. It should be noted that, after precipitation and separation of lead carbonate, the sodium chloride solution is restored to its original composition by the addition of make-up reagents and returned for another lead-sulfate leaching cycle. The solid residue obtained after leaching lead-sulphate, is leached in thiosulphate solution, with the addition of an activator, a catalyst and lixiviant for gold, to yield a thiosulphate solution of gold and silver. Since the content of gold and silver in solution is low (below 1 mg/dm3), they are first electrolytically concentrated on steel cathode and then refined to pure metals using well-known chemical methods. Note that, after the electrolytic separation of gold and silver, thiosulphate solution is recycled to the leaching step."

Jan 1, 2018

By X. Y. Liu

A culture-independent approach based on 16S rRNA gene clone library was used to analyze the bacterial community change both associated to the solids and in the liquid phase during pyrite bioleaching process. Phylogenetic analyses of 16S rRNA fragments revealed that the retrieved se-quences mainly related to genus Leptospirillum, genus Sulfobacillus and genus Acidithiobacillus. During the bioleaching process, genus Leptospirillum trends to grow associated to the solids while major of genus Sulfobacillus were in the liquid fase, only accounting little portion in the solids. Genus Acidithiobacillus can grow both on the solids and in the liquid phase, but accounting high portion on the solids.

Jan 1, 2014

The introduction and subsequent ascendancy of autogenous and semi-autogenous milling for comminution circuits has undoubtedly lead to many economic advantages. From a process viewpoint, however, at least one downside has been the sensitivity of these machines to process input variations. Foremost among these is ore competence, though feed size comes a close second. This sensitivity is due to the reliance of ag/sag mills on the feed ore for their grinding media competence and size. Autogenous (ag) mills are the most sensitive in this respect with semi-autogenous (sag) mills being increasingly less so as the ball charge is increased. Increasingly designers and operators are recognising the importance of feed size and the benefits of manipulating it to improve performance. This has been achieved by installing additional crushing/screening capacity ahead of the ag/sag, better operation of the primary crusher, better control of segregation cased by stockpiles and bins and by changing blast design/practices to modify the ROM size distribution. This paper describes the influence of feed size distribution on ag/sag mill performance with reference to a range of plant data. It particularly concentrates on how changing blasting practice to modify ag/sag feed size can have a considerable overall benefit.

Jan 1, 2003

Incomplete liberation of mineral particles is one of the key factors limiting the performance of industrial flotation circuits. This work aims to quantify the relationship between different breakage modes and how these affect mineral liberation properties. A copper porphyry (bornite) ore sample was subjected to breakage using a piston-die compression unit and an impact mill. The particles produced as a result of each mode of breakage were then characterised using Mineral Liberation Analysis (MLA) to quantify the mineralogical and liberation properties of the progeny particles. The impact mill was found to produce bornite that was finer grained relative to the host particles. In con-trast, bornite discharged from the piston-die unit closely followed the size distribution of the host particles and was retained to a greater extent in the larger/intermediate size fractions. The results provide insight into what breakage methods are optimal for the purposes of downstream separation.

Jan 1, 2014

By G. S. Hansford, G. E. Searby

The rate of bioleaching of pyrite at 70ºC by a thermophilic archaeal culture was measured as a function of the solution redox potential by the staged addition of pyrite to a batch system. The results were compared to the rate of ferrous iron oxidation over the same potential range to determine the applicability of the multi-sub-process leaching mechanism developed for mesophilic bioleach systems.

Jan 1, 2003

By Przybycien Krzysztof, Tumidajski Tadeusz

"Materials being the feed to mineral dressing plants are the mixture of ore minerals having different physicochemical properties among others, especially susceptibility on crumbling. During exploitation of material and their preparation to communition the big number of narrow classes comes into being and they have different properties. The determination of common communition laws of multicomponent (on account of size and mineralogy) materials leads to the estimation of mutual influence of narrow classes and their rates, taking into account their endurance and mineral density, on general ratios and their simultaneous crumbling.If we try to accept the grain membership to the certain component as the differing feature, we can write the balance equation as: ( ) ( ) S= = k i i i g x p f x1where: fi – density functions of one type distribution and of different statistical moments (characterising the homogeneous materials grinding), pi – “stirring” proportions of each components, S== k i i p 1 1 . From the point of verification view of detailed versions of this equation the inverse operation should be done: in the base of the components’ mixture grinding results and the results of components grinding the legitimacy of equation should be checked.The using of finished distribution mixtures’ theories to the grinding process analysis allows, first of all, to verify the assumption of grinding independence of individual feed components. Talking more generally it would lead to the comparison of grain size distributions, obtained by individual components grinding from the defined in the mixture distributions theory calculations. One of experimental and calculation results for artificial mixtures of galena and dolomite is presented on figure below (df means distribution function)"

Jan 1, 2003

By B. C. Qi

"In water treatment, flocculation or coagulation with aluminium or ferric salts has been widely used for many years to remove natural organic matter (NOM), including humic acids. However, the adsorption of NOM to aluminium hydroxide flocs during conventional coagulation/flocculation processes is very complex, with the flocculation of aluminium hydroxide particles and the adsorption of NOM molecules on flocs occurring simultaneously. Any effect on the surface characteristics and micro-structures of the humic acids and aluminium hydroxides could affect the adsorption efficiency.It has been widely observed that if a reaction system (liquid-liquid or liquid-solid) is exposed to an ultrasound field, under appropriate conditions, a variety of physical (emulsification, aggregation/flocculation) or chemical (the production of radical and exited species; single electrotransfer) actions may be activated. Though the ultrasound effects have been used in biological and chemical decontamination in many conventional environmental protection practices, the idea to explore the ultrasound effects in the removal of humic acids by preformed aluminium hydroxide flocs is relatively new. In this paper, the effect of an in-situ ultrasonication on removal of the humic acids extracted from the acidification fermentation of lignocellulosic residues, by a preformed aluminium hydroxide, was evaluated; the effect of ultrasonication on the surface complexation of the humic acids with the preformed aluminium hydroxides was investigated."

Jan 1, 2003

By A. K. Mukherjee

In this apparatus closed sized particles are placed in a container and then fluidized by passing water through the load of particles. Water flow is adjusted to deposit particles in one or more layers depending on the specific gravity of each of the particles, after which the deposited particles are separated in portions of different specific gravity. The obtained portions represent different ore content of the closed sized fraction. The process is repeated for all other size fractions to generate washability curve of the feed. Three different types of iron ores and one coal sample are tested in this equipment. The theoretical yield-grade curve generated for iron ore feed is unique in absence of any such practice for ore minerals. Similar curve is generated for coal and it is compared with washability curve, an existing practice followed worldwide. This comparison validates the performance of the process and the equipment.

Sep 1, 2012

By Al Cropp, Julie Hunt, Will Goodall, Ron Berry, Dee Bradshaw

Geometallurgy aids the understanding of ore body variability but has the most value if the data is easily available along the entire mining value chain. This requires cross-discipline communication and collaboration across traditional silos, and an organizational culture that encourages that to flourish. Data that are collected by the numerous groups (i.e. mining, geology, milling, processing, refining, smelting, marketing, environmental etc.) involved in the mining process may have relevance to other stakeholders; mineralogical and textural data for example has value to all these groups. Data required for modeling comminution or identifying acid potential from waste rock may already exist, however it needs to be made available to all the relevant stakeholders in the right format at the right time. As part of the GeM (AMIRA P843 & P843A) project the opportunity has been taken during the sponsor meetings, short courses, case studies etc. to ask the question: ‚What information do you want from further up the chain?? For example, to metallurgists ‚What information would you like from the geology group before the ore enters the mill?? The geology group may already have information important to mineral processing but not know it is of interest. This could, for example, be in the form of a geometallurgical drill core log that contains quantitative measured values. This paper focuses on the interaction between the mining, geology, mineral processing and environmental groups, using ore properties resulting from geological alteration to identify potential impacts throughout the mining process and discusses how a cross discipline approach can benefit all.

Jan 1, 2014

By Grigory Voyloshnikov, Sergey Petrov, Vladimir Petrov

"The treatment of high-grade copper gold-bearing ores is practiced extensively. However, due to low concentration of copper the application of a separate process for copper recovery can make this process uneconomical. The copper, in particular: in oxide minerals, intensively bounds with cyanide during conventional cyanidation. In this case, cyanide is not able to react with precious metals and the consumption of cyanide increases. The resulting copper cyanide complexes have a negative effect on the recovery of gold. Due to decreasing of the process parameters, a repeated use of the recycled solutions can be hindered, especially in the case of heap leaching. The technology of copper removal from the process solutions with simultaneous regeneration of free cyanide from copper-cyanide complex and producing of a saleable high-grade copper concentrate was developed. An important feature of this technology is simplicity, the absence of complex or dangerous operations and the use of common reagents. The choice of equipment depends on the ore treatment option: heap or vat leaching. Also, simpler equipment schemes are available. The studies, tests and industrial practice show that if the concentration of copper can be decreased down to the first numbers of mg per ppm or lower, it is reasonable to maintain the process copper grade in the recycled solutions at 30-50 mg/L. In this case, recycling of cyanide-bearing solutions is unlimited. The regeneration of free cyanide from that of bound with copper and other cyanide complexes is 95-98%. The grade of copper in the concentrate is 55-60%. This technology is an economically competitive option, in particular: with the account of the sales of copper concentrate. The removal of copper has a positive effect on gold recovery, especially during heap leaching. In addition to, this offers significant benefits in reduced costs."

Jan 1, 2014

By Zhou Junwu, Sun Chuanyao, Wang Fuli

"In this present paper, the authors introduce the artificial neural networks into the modeling of the industrial flotation process, integrating information technology, control theory and intelligent optimizing method to flotation technology. The new idea gives a new way to solve the difficulty in this field, and therefore brings the study on the automatic control of flotation process in China into a new start.The Radial Basis Function (RBF) network, featuring a quick learning speed, is one of the feedforward neural networks. It has attracted much attention from automatic control recently for its implementing the nonlinearity mapping through adjusting the parameters of the nonlinearity transfer function. One of the online adaptive learning algorithm—the nearest neighbor-clustering algorithm, which can automatically determine the number of hidden units, has been implemented in the MATLAB programming language in this paper, laying the foundation for the flotation models.The relation model between ore pulp characteristics and reagents consumption has been proposed using the RBF networks based on the industrial lead rougher flotation of lead & zinc ore, and the simulation has been conducted in the laboratory with the results matching the samples data very well. The Xilin Lead & Zinc Mine Flotation Process Intelligent Consultation System of Reagents Consumption, which suitable for industrial process, has been developed. The reagents consumption advised by this system would stabilize the flotation process, and increase the recoveries. It could be used for providing the technological consultation to flotation operators in site, and for training new operators."

Jan 1, 2003

By Takashi Furuyama, Sukeyuki Mori, Takafumi Okuma, Norio Hashiguchi

"In order to achieve a high recovery of particles finer than 10µm, three types of dry Tower Mill (VD-1, KD-1, KD-2 and KD-3) have been developed. These mills differ from each other in the size of the comminuting part, the inside diameter and shape of the classifying part and the system involved in the collecting process. The last version (KD-3) of tower mills in which the comminuting and classifying operations has been separated, can produce particles finer than 10µm from a limestone ore sizing from 420 to 3360µm. In this tower mill, products in comminuting section are blown up and transported into the classifying column, made of an inverted cone on top of a cylinder, before they agglomerate and settle down. Fine particles are deported and recovered in a cyclone with a central spiral ribbon.Previous studies on the grinding efficiency of the tower mill KD-3 have shown how the maximum size of collected products increased with the airflow velocity, disturbing in the same way a smooth regulation of the grinding operation with the tower mill KD-3. A complete knowledge of factors that influence the maximum size of collected products is needed, therefore, to increase the efficiency of the grindingclassifying operation and ensure a better control over the collected products. The present study deals with this issue and, assuming that the structure of the classifying column could be one of these factors, its internal structure was modified (insertion of vertical plates, cone or horizontal nets) before carrying out comminution tests that would establish a relationship between the inward shape of the column and the maximum size of collected products. It was found that the weight of products collected in the cyclone decreases when a cone or some horizontal nets are inserted inside the column. At the same time, the weight of products collected in the column increases. This is due to the fact that coarse particles blown up from the comminution section collide with the base of the cone or the nets and settle down the bottom of the classifying column. Therefore, the cone and some horizontal nets inserted inside a classifying column, have the particularity to stabilize the maximum size of particles (15.1-17.5µm and 8.4-11.3µm) in the cyclone even when the airflow velocity in duct increased. These tools could of great help in the production of particles of definite size to fit for instance the paper industries requirements (production of limestone material sizing - 10µm as paper filler)."

Jan 1, 2003

By Markus Dammers, Christopher Robben, Hermann Wotruba, Christian Schropp

"In most underground mining processes the entire extracted ore is transported from underground workings to surface processing plants for separation of valuable minerals and gangue material. Most of the transported material consists of barren rock with negligible metal content, especially for low grade deposits, such as in the copper or gold metal ore mining. Increasing mining depths result in higher costs for transportation and hoisting. Therefore, rejecting waste rock as soon as possible from the material stream gains importance. The concept of resource to product integration in the form of earliest waste rejection in combination with subsequent backfilling follows the philosophy of ‚leaving waste underground?. Implementing mineral processing underground can lead to less required mass movement to surface, hence reducing transportation and hoisting costs. At the same time, rejected waste can be used as backfill to increase extraction rates by reducing pillar volumes. In the mill, a stable high grade feed leads to decreased specific operating and investment costs as well as increased productivity and recovery. These effects as a whole have a large potential to reduce cut-off grades so that resources can be turned into reserves. Within the I²Mine (Innovative Technologies and Concepts for the Intelligent Deep Mine of the Future) project of the European FP7, investigations are carried out by the Unit of Mineral Processing of RWTH Aachen University, the Institute of Mining Engineering I and TOMRA Sorting Solutions | Mining. One aim of the cooperation is to develop new concepts for a comprehensive integration of near-to-face processing in combination with backfill into the overall underground mining process. Effects on up-, down- and side-streams are investigated to prove the potential of resource to product integration in comparison to common underground mining systems and processing methods."

Jan 1, 2014

By S. Banisi, A. Haji-Zadeh, H. Asadi, M. Maleki-Moghaddam

One area in AG/SAG milling field which has received a great attention is the optimization of liner design for any application to increase the availability of mills. The Gol-E-Gohar iron ore concentration plant uses three 9m × 2.05m autogenous mills (AG) in parallel in a dry operation. The AG mill shell is lined with three series (57 cm each) of 36-row liners. Due to large variations in feed characteristics and inadequate blending, the performance of AG mills has been lower than the target value. Therefore, to improve the comminution efficiency, the optimization of the design of AG mill shell liners was applied in this plant. By simulation it was found that increasing the liner lifter face angle from 7 to 30° while maintaining the original lifter height (i.e., 22.5 cm) could provide an appropriate charge trajectory. Measurement of the wear profiles of shell liners indicated that the wear along the liner length was not uniform and the highest wear occurred between 0.5 m and 1.2 m of the mill length. A new liner design was proposed by redistributing the metal from parts with a lower wear rate to the parts with a higher wear rate to arrive at a uniform wear profile along the liner length at the liner removal time. The non-uniform shell liner was constructed and installed in one of the three parallel dry AG mills. It was found that the first and second liner designs increased the mill throughput by 2.6 and 7.5%, respectively. After conversion to SAG milling on the account of liner change, 18% (from 413 to 489 t/h) increase in throughput was realized. It was predicted that the non-uniform liner designs will increase the liner life time by 10% and will reduce the scrap metal from the current value of 59% to 50%.

Jan 1, 2014

By W. Z. Yin

With increasing of mining depth, many iron ores in Liaoning Province contain carbonates such as siderite and ankerite. The emergence of these carbonates in ores creates a fatal impact on the running producing process of anionic reverse flotation in Dong Anshan Sintering Plant, which leads to ?concentrate and tailing no separated?. And its reason is still unknown. Moreover, siderite, despite that its ferric theoretic grade is only 48.2%, however, do not affect the blast furnace utilization factor, therefore, can be used as raw materials in ironmaking. In order to solve the separate problem of iron ore containing carbonates, five pure minerals, martite, magnetite, quartz, siderite and ankerite, were selected for a series single flotation experiment. The aim was to discover the flotation difference of these minerals, furthermore, to explore a new flow sheet for the iron ore containing carbonates. The results of single mineral flotation experiment reveal that the combination regulators, starch and CaCl2, in different pH extent, can make these minerals taking on obvious flotation difference, which make it possible to process the iron ore containing carbonates. A new flow sheet, step-flotation, to process iron ore containing carbonates is explored, that is, first step, direct-flotation processing, is to eliminate the bad effect that the carbonates bring in flotation system by collecting carbonates under neutral condition; the second step, reverse?flotation processing, is to get qualified iron concentrate by collecting quartz under alkaline condition. Manual mixed ore sample were processed successfully through this new flowsheet under proper reagent system, which has absolute advantage compared with routine flowsheet. Actual ore sample of compound magnetic separation concentrate were processed successfully both open and closed circuit experiment through this new flowsheet. SEM and EDS were used to probe the reason why carbonates affect the regular processing. It is analyzed that moderate floatability of siderite and its coating on the surface of hematite and quartz make the phenomenon ?concentrate and tailing no separated?. This research provides a reasonable processing scheme for iron ores containing carbonates and can be used for reference in processing other complicated, refractory iron ore.

Jan 1, 2014