Search Documents

By Alex Joseph

A tertiary amine containing polyamine in its back bone was grafted to exfoliated graphite oxide by means of a series of chemical reactions.The synthesized amine functionalized polyaniline grafted to exfoliated graphite oxide (EGAMPANI) was characterized using various techniques such as, FTIR, TGA, Raman, and X-Ray diffraction.The synthesized EGAMPANI was blended with carbon paste electrode, and used to study the response of Hg2+ in acetate buffer solution.Preliminary analysis showed that the anodic current intensity using the EGAMPANI modified electrode was higher during a potential sweep and 10-4 M concentration of mercury could be detected which could be improved to 10-6 M using anodic stripping voltammetric technique. Keywords: metal sensor, exfoliated graphite oxide, functionalization, polyaniline

Sep 1, 2012

By Thi Hien Tran, Ngoc Anh Tran, Thi Thu Hien-Dinh, Duy Anh Dao

"Natural graphite exists mainly in three types of amorphous graphite, flakes graphite and lump graphite. Graphite from Bao Ha mine, Lao Cai province is with 11.8 carbon-graphite %, forms in flakes and dense crystals. The paper presents the comparison among enrichment of Bao Ha’s graphite by two types of froth flotation with 90 g/t kerosene oil as collector, 50 g/t montanol 800 as frother, in natural pH, and at 20 wt.% of solid. The differences among three flow charts indicated that using middling flotation and re-middling flotation for the cleaning tails and the scavenger concentrates, the final concentrate was improved and containing up to 94 carbon-graphite % of flakes graphite, up to 82 carbon-graphite % of fine graphite with 93.48 % total recovery, moreover, carbon-graphite in the final tail is 0.86 % with 6.52 % recovery. However, a refining mill and a classification stage were applied before doing the middling flotation stages.1. INTRODUCTIONGraphite (black lead or plumbago) is used in many industrial applications due to its high electrical and thermal conductivity, lubricity, and chemical inertness. High quality graphite can be used in metallurgy, molding, brake linings, batteries, and fuel cells. Graphite, composed exclusively of the element Carbon, is rather common mineral, but fine crystals are rare. Graphite is soft (hardness: 0.5-1 Mohs scale); has a layered, planar structure; occurs in platy or acicular (occasionally) morphology (Minerals.net; Pierson, 1993).USGS (2017) reported, global consumption of natural graphite continuing increase in the period of 2012-2016. In 2016, China used up 35% while produced 66% of the world’s graphite. Graphite mining are being developed in Madagascar, Mozambique, Namibia and Tanzania, but production reduced in Canada from 2015. Based on the statistic of Statista.com shows from 2011 to 2014 and a forecast to 2020, the global graphite demand is mostly in refractories, batteries, others, lubricant/crucible, foundry and pencil, and that is increase every year.Graphite Vietnam lies on the fault of the Red river from Yen Bai to Lao Cai, the reserves is estimated around 29.3 million ton and mostly in Lao Cai province where has Nam Thi graphite mine and Bao Ha graphite mine (MOIT, 2008). Vietnamese graphite products could reached to ~92% graphite carbon (Cg) (Tran Thi Hien et al., 2008). Studied samples was collected in Bao Ha graphite mine, is located in Lao Cai province. Graphite Bao Ha exists in two types as graphite flakes and amorphous (Hoang Thi Minh Thao et al., 2017)."

Jan 1, 2018

By E. V. Bratygin, E. G. Dmitrieva

The aim of the research was to study the thermodynamic characteristics of high-temperature processing of ilmenite concentrate deposits "Central" in a neutral and oxidizing atmosphere, as well as its interaction with alkaline additives. The research was conducted using a scanning colonoscopy on thermogravimetrical analyzer NETZSCH STA 449 F3. A sample of the test material weighing 10 mg was placed in a crucible and heated at a rate of 10 °C/min to 1200 °C in argon or air. Studies have been conducted pure ilmenite concentrate and its mixtures with 5 % and 12.5% of sodium carbonate. The results of the analysis of the thermogravimetric curves it was found that the recovery of the concentrate carbon will come from ulvospinel, not pseudobrookite, and the reaction recovery is possible at temperatures above 900°C. While removing produced in the decay ilmenorutile of iron oxides in an inactive form, for example, iron (III) oxide, it is possible to reduce the quantity of the solution of ilmenite formed during the restoration of the melt anosovite. The analysis of data obtained during heating of ilmenite concentrate with sodium carbonate in concentrations of 5 and 12.5% transition pseudobrookite in ulvospinel is missing, it just breaks down into hematite and titanium oxide, which, in turn, react with N?2??3. It should be noted that increasing the concentration of sodium carbonate in the sample contributes to more complete interaction of iron oxides and N?2??3 with formation of ferrites of sodium. This can ensure full recovery of iron oxides in the concentrate, which is part of secondary ilmenite can not be dissolved in the melt formed by the lower oxides of titanium. In addition, the increase in the content of soda in the mixture significantly reduces the temperature of the initial melting point of the slag and facilitates the coagulation of metallic iron.The obtained results were used for laboratory studies of the solid-phase sintering of briquettes from ilmenite concentrate with additives of sodium carbonate and a reducing – coal, as well as for the development of technological mode of solid-phase sintering of the concentrate with the aim of obtaining product recovery with a titanium dioxide content of more than 75 %.

Jan 1, 2018

By A. V. Abshilawa, D. G. Talakhadze, R. I. Sturua

"Processing of the tailings accumulated over the lifetime of Madneuli Copper Concentrator is an opportunity to extract additional salable copper and gold products. This paper presents a pre-concentration process for the valuable components (copper and gold) of the accumulated tailings. The developed process makes it possible to obtain a copper pyrite concentrate with a yield of 14.05%, copper grade of 1.36%, and recovery of 83.22% containing 3.78 g/ton of gold at a recovery of 84.31%. The bulk concentrate is produced by a combined process bringing together selective flotation to produce salable copper concentrate and hydrometallurgical processing of the selective flotation tailings to recover gold. KEYWORDS: FLOTATION, ALBION PROCESS, LEACHING, COPPER CONCENTRATE, SELECTION Madneuli Copper Concentrator, Georgia, was put into operation in 1975. Over its lifetime, 40 mn tons of tailings have been accumulated at the tailings storage facility (TSF). Sampling of the TSF has indicated that the average copper and gold grade is 0.23% and 0.56-0.65 g/ton, respectively. Accordingly, the TSF can be classified as a technogenic reserve. This paper discusses pre-concentration of valuable components using flotation, followed by processing of the bulk concentrate in the Albion process. Mineralogical analysis of the accumulated tailings showed that the main ore mineral is pyrite (11.71%). Copper minerals are mainly represented by chalcopyrite (0.7%). The main nonmetallic mineral is quartz (67.3%); sericite, chlorites, etc. also occur. Pyrite is present both as liberated grains and intergrowth. The absolute majority of copper minerals are found as intergrowth with pyrite, less often with quartz. Ore minerals are slightly oxidized. Chemical analysis results are shown in Table 1. Particle size distribution shows that the size class -0.2 mm - 0.045 mm has the highest grade of 0.85 to 0.97 g/ton of gold. Size class +1.25 mm has the lowest grade. Based on the chemical and mineralogical studies and particle size distribution, an optimized process was developed for pre-concentration of the valuable components prior to hydrometallurgical processing. Several gravitation, direct selective, bulk, and bulk selective flotation processes were trialed. (1,2)"

Jan 1, 2018

By Klaus M. Hahn, Hermann Wotruba, Bernd G. Friedrich

"Due to an increasing demand for nickel and cobalt and the depletion of nickel sulphide deposits worldwide, the production of ferronickel from lateritic nickel ores becomes more significant. About 60 percent of nickel reserves are present in laterite deposits. Common production methods like acid leaching or smelting operations implicate high material and energy consumption. Physical processing methods are also not efficient, because of the fine microstructural intergrowth of the minerals carrying valuable elements such as nickel and cobalt. Due to the high energy consumption of metallurgical treatment of lateritic nickel ore (nickel grade: 0.8 - 3.0%, Co: 0.05 - 0.15%), the separation of waste material (about 75 - 85%) before the metallurgical treatment is desirable. Therefore, an alternative process has been developed, combining a pyro-metallurgical pre-treatment with selected mechanical processing methods. The developed process consisted of a selective pre-reduction and non-selective segregation of the contained metal phases in the first stage. By this, the properties of the metal carrying minerals were changed and could become subject to concentration by means of fine beneficiation processes afterwards. The parameters of the pre-reduction and segregation were varied and the pre-treated samples were examined concerning their efficiency of metalization grade and metal grain size. This paper describes the investigation of pre-treatment methods of a lateritic nickel ore. The pre-treatment and possible subsequent separation methods were examined with regard to the recovery of the valuable elements. Metalization grade was around 80% for both Ni and Co with metal phase grain sizes below 20 µm. Scanning electron microscopy revealed distribution of new metal phases not only on the reducing agent, but also on the “slag” material.INTRODUCTION Nickel laterites are characterized as strongly weathered regoliths with several zones containing reserves of nickel (Ni) and cobalt (Co). These laterites are formed on serpentinites and ultramafic rocks under climatic and/or tectonic conditions that have changed over time (Butt & Cluzel, 2013). The formation of Ni laterites is influenced by numerous geological and environmental factors. In general, there are three ore types named according to the dominant Ni hosting minerals: oxides, hydrous magnesia (Mg) silicates and clay silicates (Butt & Cluzel, 2013). The most Ni laterite deposits contain two of these ore types, usually an oxide zone and an either clay or Mg silicate zone. Distribution of these principal deposit types, their average Ni-bearing phases and mean Ni grade are shown in Table 1. A schematic profile of the different deposits based on the development on serpentized ultramafic rocks is given in Figure 1 (Butt & Cluzel, 2013)."

Jan 1, 2018

By William Skinner, Jonas Addai-Mensah, Keith Quast, David Robinson, Jason Connor

A review of the laboratory- and pilot plant-scale physical separation techniques for the beneficiation of nickel (Ni) laterites shows limited efficacy. To date, the only upgrade technique adopted commercially, prior to hydrometallurgical processing of Ni laterites, is the removal of a barren, coarse size fraction in the feed by classification. In the present work we investigated two low grade (~ 1%), goethite-rich Ni laterite ores’ upgrading by magnetic separation, attritioning/coarse, (lower Ni-grade) gangue rejection and flotation techniques. Low intensity (0.1T) dry magnetic separation at ambient temperature of raw samples and those pre-heated at temperatures up to 450 °C showed evidence of pay metal Co and Mn bearing asbolane and/or lithiophorite minerals pre-concentration in the magnetic fractions. Ni distribution, however, did not show any noticeable magnetic upgrade but followed the weight distribution. Other ore pre-treatment methods (e.g., desliming and sulphidisation) followed by froth flotation with anionic and cationic reagents also led to noticeable (~35%) Ni upgrade. This is due to the deportment of Ni across several gangue host mineral phases (i.e. Fe oxide/hydroxide and a range of silicate/aluminosilicate minerals). From chemical analysis, after disaggregation of ~ 1% Ni grade feed ore, coarse (-600 + 38 µm) and fine (-38 µm) fractions of ~0.6% and 1.3% Ni grades respectively, were also produced, suggesting that a significant upgrade in Ni content can be achieved by rejecting the + 38 µm fraction with the loss of <40% of the Ni. The ore mineralogy, particularly the complexity and high number of un-liberated Ni-bearing phases, greatly compromises physical separation methods for these ores, with the possible exception of screening after disaggregation of the fines inherent in the run of mine ores.

Jan 1, 2014

By H. Z. Kuyumcu

Associated with the development of a novel microbiological oxidation process for the conditioning of iron hydroxide slurries from ferrous mine waters, there is a realistic chance to make the contained iron available for a material utilization. The transformation of ferrous into ferric compounds is coupled with the precipitation of iron hydroxisulphate mostly in terms of the mineral Schwert-mannite. The further treatment of the iron hydroxisulphate has to be aimed on the processing for product recovery and product refinement. For many potential applications, e.g. in the ceramic industry, the pigment industry or for metallurgical applications, the removal of sulphate is essential. For the dehydration of the iron hydroxisulphate and the sulphate removal, microwave heating technology is a beneficial method. In contrast to conventional thermal heating processes the supply of energy in microwave application takes place directly within the material through the dissipation of electromagnetic energy, i.e. no heating medium is needed. It is a volumetric heating process regardless of the surface of the material. The rapid and targeted energy supply and the good controllability of microwave heating systems are advantages which have led to a wide variety of applications in industrial processes. Among the diverse use for heating of temperature-sensitive, chemical and pharmaceutical products as well as foodstuffs the number of applications also in mineral and solid processing increases. At the Department for Mechanical Process Engineering and Solids Processing of the Technical University Berlin the use of microwave technology for the treatment of iron hydroxisulphates has been investigated systematically within the framework of a cooperative research project. The paper at hand shows results from material conversion tests subject to a variation of the relevant process parameters. The reaction products are characterized and the process is compared with the conventional heating in a rotary kiln.

Jan 1, 2014

By L. Filippov

"Nickel is an important metal with the total global consumption of about 2 million tons per year. It is sourced from both sulfide and laterite ore, but currently laterites are becoming more attractive for nickel production due to the depletion of high grade nickel sulfide ores. Laterites are generally processed by hydro or pyro-metallurgy and therefore, pre-concentration of nickel before such processes is very important. In this paper the effect different physical methods (including flotation) on the pre-concentration of nickel in laterite ores will be discussed. The ore used in this study was a laterite from South East Asia. Nickel was upgraded using different methods such as magnetic separation, flotation and sizing. The effect of ore mineralogy on choosing the best strategy to upgrade nickel will be discussed. The findings of this project will help to unlock a substantial volume of nickel with significant value from laterite ores.INTRODUCTION Nickel is an important metal with the total global consumption of about million tons per year which has grown rapidly during last decades (Mackey, 2011). Nickel is sourced from two different types of ores, sulfide and laterite. The majority (about 70%) of the world’s nickel resources occur as laterite ores which are often complex, and low grade, and therefore expensive to treat using conventional methods (Xu et al., 2013). Today, nickel laterites are more attractive for production of nickel as the amount of high grade nickel sulfide ores has diminished (Janwong, 2012). Therefore more economic processes to recover nickel from these resources should be developed.It should be noted that nickel laterite mineralogy is complex, and nickel often presents as ultrafine inclusions in a number of mineral phases. Because of the low nickel concentration and variable distribution in these phases, effective upgrading by physical separation processes would be challenging. Researchers have tried to improve nickel laterite flotation recovery by using a number of feed preparation techniques. A summary of the nickel grades obtained using flotation and magnetic separation as reported in the literature is presented in Table 1. It can be seen that only minor nickel upgrades have been reported. Quast et al. (2015) have concluded that the complex mineralogy of nickel laterite ores makes it difficult to achieve any significant nickel upgrading by physical techniques, including flotation. They achieved 40% increase in the nickel content (from 1.0% to 1.4%) at a nickel recovery of 43% (Quast et al., 2015). Various attempts in USA, New Caledonia, India and Australia, to upgrade nickel in laterite using magnetic separation have not been successful (Quast et al., 2015). A recent comprehensive review on topics influencing nickel laterite flotation has shown that further investigations in the flotation of laterite ores are undoubtedly warranted (Farrokhpay & Filippov, 2016)."

Jan 1, 2018

By J. H. Starkey

SAGDesignTM Testing for grinding mill design was introduced commercially in 2004. Up to January 2008, 18 projects have been completed and 99 samples have been tested using this method. Two papers have been published describing the patented test procedure and one of these shows how the results compare with other grinding test methods. This paper will briefly discuss the theory on which this technology is based, and explain the procedures used to develop the calibration equation. Case studies are also included to demonstrate the effectiveness of the test work being done. These case studies show how the SAGDesign test is being used today: to design new grinding circuits for commercial full scale use; to calculate throughput in existing mills for production planning; and to accurately define grinding mill requirements at the scoping, pre-feasibility or feasibility study stage of project development, in order to economically identify the size and cost of the grinding mills that will be needed for the project. This is important because if the full rec-ommended SAGDesign testing program is done at an early stage in the project, the definitive cost for a guaranteed throughput, grinding mill design (by Outotec if their mills are purchased) is available. New grinding mill design for final engineering will be represented by the test work done on the Climax Molybdenum Project for Phelps Dodge (now FMI) in Colorado, USA. The SAG mill and ball mill for Climax are now in fabrication with project start up in late 2009. Next, the sizing of grinding mills at the scoping, pre-feasibility or feasibility study stage of mine development will be represented by a large metal mining property in Russia. Finally, calculation of the throughput for existing mills will be represented by work done at a base metal mine, in eastern Canada. Test work for designing SAG mills is now done in four laboratories at the time this paper was written. One in the USA at Dawson Metallurgical Laboratories, Inc. in Salt Lake City, two in Russia at the TOMS Research and Design Institute and at the Irgiredmet Research Institute, both in Irkutsk, and a fourth mill has been installed in Australia at AMMTEC Limited?s lab in Perth. A fifth SAGDesign test mill for radioactive ores has been built by Starkey & Associates, specifically for testing uranium ores and can be moved to any licensed lab in the world on a project basis.

Jan 1, 2014

By O. A. Bascur

It is difficult to analyse the economics without an integrated view of mine transactions, stockpile inventories, process flows and assays. The lack of integration of mining and metallurgical information with sufficient detail to analyse and act is a problem. However, to take action requires real time information from manufacturing assets, corrected for gross errors from trucks, shovels, conveyors, faulty sensors, bad instrument calibration. Validation methods use process models to identify inconsistent information in the case of corrupt actionable information. This paper presents new strategies that transform the data into business information for continuous improvement and optimization. This technical presentation will review recent implementations enabling large metallurgical complexes to improve their data quality for overall production and energy management. A competence center emerges as an enabler for implementing operational intelligence. The evolution of Web services to troubleshoot plant information and to collaborate at the enterprise level is presented.

Jan 1, 2014

By B. Tora

The new method of evaluation of grindability of hard coal and its blend is shown. Standard Hardgrove test is used as a base to work out this method. The essence of this method consists of simulation of milling process in close circuit (mill-classifier) and determination of energy consumption and quantity of product under the constant feed flow. The research equipment designed specially for this project is described New method of grindability measuring completes standard Hardgrove method withdrawing its faults: ? bigger (c.a. 10 times) and more representative sample is used; ? the milling process is carried out in close circuit (similarly to the industrial condition); ? energy consumption of the milling process is determined for three samples, which differs in grain size. The new method of evaluation of grindability of hard coal and its blend is shown. Standard Hardgrove test is used as a base to work out this method. This method allows us to determine energy consumption of the milling process. The essence of this method consist of simulation of milling process in close circuit (mill-classifier) and determination of energy consumption and quantity of product under the constant feed flow. Our results will complete the Hardgrove method and will help us to better characterise coal. At the same time investigations in industrial scale are carried out. These investigations will verify this new method. Also a new mathematical model of the milling process is being elaborated. It will be used to predict behaviour of coals in industrial conditions.

Jan 1, 2014

By H. Deng

Oxidized zinc ores are the main source of zinc metal except sulfides. To have a better understanding about the performance of smithsonite and the main gangue, quartz, in flotation, the aggregation behaviors of smithsonite and quartz in water were confirmed by different techniques (sedimentation tests and optical microscopy). The experimental results show that smithsonite and quartz particles aggregate in the pH range 7.5-11. The results of zeta potential suggest that the aggregation does not correlate with the DLVO theory, when the iso-electric point of smithsonite and quartz is 8.0 and 2 respectively. When the solution pH is less than 8.0, smithsonite has an opposite charge to the quartz particles. Electrostatic adsorption makes effort on these two kinds of particles according to DLVO theory. Whereas, solution chemistry calculation shows the pH range 8-11 corresponds to hydroxide formation, suggesting that this is the species responsible for aggregation. And their concentrations are much higher in sodium hydroxide system than that in sodium carbonate system. Aggregation of smithsonite and quartz due to the flocculation action of zinc hydroxide is proposed.

Sep 1, 2012

By A. N. Zagorodnyaya, T. N. Bukurov, Z. S. Abisheva, A. S. Sharipova

"This work presents the results of the development of a flowchart for the processing of copper production dusts resulting in the production of of lead sulphate, tribasic lead sulfate (TBLS), ammonium perrhenate, zinc, copper-cadmium cake.Dust having the following composition (wt. %): Pb 39.3, Zn 6.5, Cu 5.5, Stotal 10.8, As 1.05, SiO2 0.6, Cd 0.8, Bi 0.04, Ag 0.02, Re 0.03 was used in the work. Chemical and X-ray analyses indicated that lead, zinc and copper are generally present in dusts in the form of sulfates, various amounts of oxides, sulfides, silicates; sulfur (according to chemical analysis data) is present in the form of sulfates (~ 90%) and in the form of sulfides (~ 10%).Studies have been made on two-stage stripping of copper production dusts containing lead, zinc, copper, cadmium, rhenium in the form of various compounds, at first with soda solution, then with nitric acid solution. It has been indicated that the combination of the operations allows the recovery of 98% rhenium, 82% lead, 92% copper, and 96% zinc and cadmium each in the solution. Furthermore, at the stage of dust leaching with soda, 80% of rhenium and 0.01% of nonferrous metals each are recovered in the solution. Remaining quantities of all metals are recovered in nitric acid solution up to maximum values. Such behaviour of metals is caused by metal phase content in dusts and properties being formed during leaching of compounds. At the stage of dust leaching with soda solutions, carbonates with various compositions are formed due to the exchange reaction between nonferrous metal sulfates and sodium carbonate. The conversion of PbSO4 into PbCO3 is apparently occurs in the solid phase and the conversion of readily watersoluble zinc, copper, and cadmium sulfates into that of carbonate salts occurs in the liquid phase. Rhenium passes into solution due to the presence of rhenium greater quantity in dust in the form of readily soluble perrhenate. Some portion of the perrhenate is, probable, blocked by lead sulfate and liberated in the conversion of PbSO4 into PbCO3."

Jan 1, 2003

By A. Güney, G. Önal

"Karagedik Chromite Concentrator of the ETI Holding Co., which is located in Fethiye (south Turkey), has been producing chromite concentrate assaying 47-48 % Cr2O3 from the chromite ores containing 30-35 % Cr2O3 by using gravity separation methods since 1920. The tailings having 13-14 % Cr2O3, which had been removed from this plant, were accumulated at the stockpiles amounting about 1.2 million tons. In order to recover the ultra fine chromite particles from the Karagedik Concentrator tailings, the new process including Wet High Intensity Magnetic Separation and column flotation, was developed and the Karagedik Research Pilot Plant based on this process was commissioned in 2000. At this plant, the final concentrates assaying 46-48% Cr2O3 were produced and overall plant recoveries are about 60-65%.At the chromite concentrators using gravity separation methods, if their material size is about minus 1.0 mm, chromite particles especially pass to fine fractions according to their mineralogical structures and the ore-genesis (Önal and Güney, 1990). Generally, after crushing and grinding, the shaking tables and spirals are used at the chromite concentrators; therefore fine size chromite particles (-0.038 mm) are removed as tailings. Cr2O3 content of the -0.1 mm size fraction with 52.3% of the total amount is 19.58 % with Cr2O3 distribution of 82.6%.In order to upgrade the minus 0.1 mm size fraction of the tailings, assaying about 20% Cr2O3, Karagedik Research Pilot Plant (KRPP), which includes Wet High Intensity Magnetic Separator (WHIMS) and Column Flotation units, was installed by Istanbul Technical University (ITU), Mineral Processing Section in 2000.Feeding material of the KRPP having 5 tons per hour capacity is obtained from stockpiles amounting 1.2 million tons. After attrition scrubbing, the feed is sent to a screen with aperture of 1.0 mm. The screen overflow, assaying 5-6 % Cr2O3 is removed as tailings. Screen underflow is classified to –1.0+0.1 mm and minus 0.1 mm size fractions by using cyclone and sieve bend. –1.0+0.1 mm size fraction assaying 6-7 % Cr2O3, is sent to existing gravity separation plant. Minus 0.1 mm size fraction is firstly fed to WHIMS for pre-concentration and non-magnetic product assaying 10-11 % Cr2O3 consisting of serpentine, talc and olivine minerals are separated as tailings. Also magnetic product (25-30 % Cr2O3) obtained from WHIMS is fed to the two stages conditioners after dewatered to 30 % solid ratio."

Jan 1, 2003

By M. M. Moghaddam

Charge motion is of prime importance in the efficiency of comminution in tumbling mills. Since direct observation of charge shape and its motion in industrial mill are not possible, a combination of analytical and physical studies was used to determine charge trajectory. Software packages, which predict charge motion such as the GMT (Grinding Media Trajectory) only consider the outermost layer of charge (single ball) and ignore the interactions of grinding elements. In this research, the measured charge trajectory in a 1m-diameter mill with the transparent end, called model mill, was compared with that of the GMT. Four types of polyurethane rings were accurately machined to scale down the liners arrangements at two industrial mills. To explore various charge shapes and trajectories, the model mill was operated at 55, 70 and 85% of critical speed for five levels of mill filling (10, 15, 20, 25 and 30% by volume). The angular displacement of the toe, toe departure, shoulder and charge impact point were determined from the photographs taken from the model mill. New relationships to predict charge shape and charge impact points were introduced to modify the GMT results. The relationships were validated by the model mill using the new liner of the Sarcheshmeh copper complex SAG mill. The relative error of prediction was found to be 1.1%. The results indicated that when the lifter face angle increased from 7 to 30º, the distance between the charge impact point and the toe decreased from 52 to 31º for 25% filling. This meant increasing the probability of charge impacting the toe not the liner which favoured more efficient comminution practice. After converting AG mills to SAG mills on account of liner profile change, 31% increase in throughput (from 419 to 548 t/h) in addition to 4% decrease in the product size (from 516 to 496 µm) were realized which was a significant contribution in the plant performance improvement.

Sep 1, 2012

Cyanide is reactive to copper minerals and is not suitable to extract the gold from the copper bearing ores. Ammoniacal thiosulfate is considered an excellent alternative lixiviant for leaching copper bearing gold ores. Unfortunately the results of high reagent consumption and poor gold ex-traction were found by thiosulfate leaching of synthetic gold ores containing chalcopyrite, chalcocite or bornite and a mild refractory copper-bearing sulfidic gold ore. In this investigation, several processes have been applied to reduce the impacts of these minerals on gold leaching. The process included: the pre-oxidation of copper sulphide minerals in water or ammonia solution, the reduction of dissolved oxygen in the lixiviant (0.3 ppm DO or 0.7% oxygen), adding phosphate anion in the leach or pre-leach stage, and the addition of a strong copper ligand (e.g., EDA and DETA). The results indicated that the gold extraction could be improved to 93% with the thiosulfate consumption being reduced to less than 8 kg/t. The dissolution of copper minerals was found to be the major reason for increased consumption of thiosulfate and the highly reductive leached surfaces are responsible for the reduced gold extractions.

Jan 1, 2014

By Weiran Zuo, Narayan Krishnan, Frédéric von der Weid, Emmy Manlapig, Fengnian Shi, Klaas van der Wielen

Laboratory study has identified a new application of high voltage electrical pulse technology for pre-weakening ores. In recent years, the Julius Kruttschnitt Mineral Research Centre (JKMRC), Newcrest Mining and SELFRAG AG have conducted joint research in validation of pre-weakening of SAG mill feed through the pilot scale tests and comminution circuit simulations. Ten tons of SAG mill feed with a top particle size 150 mm were tested with two pilot scale SELFRAG machines installed in Switzerland. A simulation study using JKSimMet software was carried out to find where the high voltage pulses pre-weakening technique can be best applied in a gold-copper ore comminution circuit, based on the data of the pilot scale SELFRAG tests. A novel comminution circuit was designed, which incorporated SELFRAG to pre-condition part of SAG mill feed (9.5 to 150 mm) and to treat the circulating SAG mill pebbles. The high voltage pulse technology effectively reduced the amount of ‘critical size’ particles in the SAG mill and pre-weakened particle strength for grinding. Attributing to the nature of bi-modal size distribution and the significantly reduced F80, the simulations showed that the SAG mill had spare capacity to process part of hydrocyclone underflow from the secondary ball mill grinding circuit. The simulations indicated that the novel comminution circuit had the potential to remove two MP1000 pebble crushers and one 10 MW ball mill from the existing 2000 t/h grinding circuit. A 5 kWh/t energy reduction by adopting the novel comminution circuit in a gold-copper operation may be realized. This would result in substantial savings in operation costs.

Jan 1, 2014

By Grant C. Lukey, Jannie S. J. van Deventer

"The environmental effects of the mining and mineral industry include destruction of natural habitats, changes in river regimes and water tables, and other serious ecological impacts. In this century, it is likely that water will become a critical resource, and in most countries the mining industry competes for a share of this resource. The Kyoto Protocol may at first seem only relevant to the coal mining and power industry, however, it should not be forgotten that the mining and mineral industry is a significant consumer of power. Therefore the ratification of the Kyoto Protocol by most developed countries and the introduction of a carbon credit trading scheme will impact on the industry by potentially increased costs in utilities and waste discharges. It is clear therefore that the mining industry faces many challenges in the coming years. The mining industry?s commitment to sustainable development needs to continue to evolve, in order to meet these challenges effectively. With the advent of globalisation of the industry, it is now an opportune time for the industry to gain international agreement on how they want the industry to achieve sustainability in future years; such a progressive approach is necessary, otherwise government will force the industry to change, which may not necessarily be the best outcome for the industry.INTRODUCTIONThe Earth Summit in Rio de Janeiro in 1992 was an opportunity for world leaders to assemble and discuss strategies and initiatives that provide for further industrial growth without adverse effects on the environment. The World Summit on Sustainable Development held last year in Johannesburg, South Africa, was an opportunity to evaluate those initiatives implemented over the past 10 years, and to set a new and sustainable direction for the future. It is clear that industrial and technology development will continue at a rapid pace in order to serve the needs of a growing world population, but it is essential that the course of this development is well planned, well executed, and that it is sustainable. In reality, while government officials and politicians continue to debate policy and international protocols, the environment continues to suffer and the effects of climate change and global-warming become more real each day."

Jan 1, 2003

By Yuexin Han, Jie Liu, Shuai Yuan, Yanjun Li

"In order to improve recovery efficiency of iron minerals from iron ore tailings and to reduce its connected environmental pollution, this article investigated the reducing roasting of iron ore tailing in a laboratory fluidized magnetization roasting reactor to optimize the roasting method and conditions. The examined parameters included roasting temperature, roasting time and reducing atmosphere. The parameters evaluating magnetizing roast efficiency and theoretical value were determined. X-ray diffraction (XRD) analysis was used to investigate the conversion of iron phase after roasting. The results show that the best magnetizing roast conditions are roasting temperature of 540?, holding time of 15min, and CO concentration of 20%. The magnetization conversion ratio of roasting products is over 80%, under the best magnetic separation condition, the concentrate grade of iron is 65.61 % and the recovery of iron is 83.77 %. The XRD analysis shows that Fe exists in hematite and siderite before roasting and exists in magnetite after roasting. The technique not only recovers the iron minerals from tailings with good economic benefit, but also reduces the environmental pollution of tailings accumulation.INTRODUCTION Iron ore tailings are the solid wastes generated during the beneficiation process of iron ore concentration and are one of the main pollution concerns in the mining industry (Das et al., 1996). Continuous development of the iron and steel industry has led to the increasing amount of iron ore tailings; there are over 300 million tons of iron ore tailings discharged per year (Rao et al., 2016). The huge amount of stockpiled iron ore tailings brings a series of environmental and social problems. Comprehensive utilization of iron ore tailings can not only reduce environmental load but also conserve resources, promoting sustainable development of the society. In recent years, iron ore tailings as secondary resources have received considerable attention in many countries in the word and numbers of studies on utilization of iron ore tailings were carried out, such as recycling the valuable minerals (Datta et al., 1996; Jia et al., 2013; Panda et al., 2018), used in construction material compositions as alternative source of raw materials (Das et al., 2012; Zhou et al., 2012; Luo et al., 2016) and other utilization. The iron minerals were recovery by magnetization roasting (Rao et al., 2016; Yang et al., 2013; Yang et al., 2011) and flotation (Kumar and Mandre, 2016). By comparison the reduction roasting has more advantages, but it was found that the conventional roasting equipment was inefficient, high energy consumption and un-economically applied on an industrial-scale."

Jan 1, 2018

The challenges of nature for the recovery of metals for a sustainable future continue to present in diverse ways. Base metal deposits are becoming lower grade and more complex. Rare earth metal demand is soaring and must certainly be met from new sources outside of China. Precious metals have soared in value due to increased industrial usage and the importance of these metals as financial instruments. Many of the future sources of precious metals are complex and difficult to process. The field of hydrometallurgy plays an important role in providing technology for extraction of these metals for a sustainable future. Selected examples from the base, rare and precious metals fields will be used to illustrate how current developments are providing metals for our future. The recovery of rare earths by beneficiation, leaching, purification, precipitation will be described from a multi-mineral deposit in Canada. The recovery of metals from complex base and precious metal ores may be accomplished using chloride ? assisted high temperature pressure leaching. Finally, by way of example, the enhanced Galvanox? process for treatment of chalcopyrite concentrates using silver-activated pyrite as a catalyst will be illustrated. This process offers a viable alternative to the conventional smelting of chalcopyrite copper concentrates.

Sep 1, 2012