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By P. V. Ramesh Babu

India has sizeable number of small deposits of rare metal bearing minerals namely columbite-tantalite, pyrochlore, beryl, lepidolite, spodumene and rare-earth element bearing minerals monazite and xenotime in different parts of India. Pegmatites, alkali granites, syenites, and the derived gravel and soils are the main source for rare metal and rare earth (RMRE) minerals. The RMRE minerals are classified as prescribed substances under Atomic Energy act of 1962 keeping in view the uses in the nuclear industry. Atomic Minerals Directorate for Exploration and Research (AMD) of Department of Atomic Energy (DAE) is the sole agency responsible for exploration and exploitation of RMRE minerals in India since 1962. The latest technological advancements and applications in the field of space, electronics, communication and nuclear industry using these metals and their products have necessitated to augment the production and resources of RMRE minerals. These minerals play a significant role in the technological and economic development of the country. The light rare earth element bearing mineral monazite is abundant in beach sands and is being commercially exploited by Indian Rare Earths Limited (IREL). Columbite-tantalite, the chief source for niobium and tantalum (Nb-Ta) metals present in the pegmatitic gravel are recovered by small mobile beneficiation plants. The cut and fill method of mining adapted is eco-friendly. The processing flow-sheet consists of wet sizing at ½ in and 1mm followed by gravity concentration of sized products utilizing the methods of jigging and wet tabling. The sizing equipment include revolving and vibratory screens and the gravity concentration equipments used are fixed sieve jigs and movable screen jigs for final upgradation. The gravity concentrates are further upgraded by magnetic separation to remove magnetite and ilmenite. The mine areas are reclaimed by filling with coarse size tailings and new plantations. These mobile pilot plants were earlier operated in Bihar mica belt, Jharkhand, pegmatitic areas of Karnataka and Nellore mica belt of Andhra Pradesh and are currently being operated in Bastar-Malkangiri pegmatite belt of Chhattisgarh and pegmatites of Jharsuguda district of Orissa. Beryl, lepidolite, spodumene and cassiterite minerals are the by-products from the pegmatite ores. Fergusonite, samarskite and microlite are the other niobium and tantalum bearing minerals which are also found in pegmatites. Xenotime, the chief mineral of yttirium generally occurs in granites and pegmatites. The rare earth minerals monazite and xenotime get concentrated in the placer sands of rivers and beaches. The occurrence of xenotime in the sands of Siri River and Deo River in Chhotanagpur granitic terrain in parts of Chhattisgarh and Jharkhand are an example. These sands containing 1-2.5% heavy minerals were processed by a mobile plant consisting of sizing equipments like trommel and vibratory screen followed by separation of heavy minerals from -1mm sands with the help of gravity concentration equipments like spirals/shaking tables/sluices. Xenotime and monazite from the pre-concentrate are further separated by magnetic and electro-static methods. The present paper illustrates the pilot plant set up for the recovery of rare metal as well as rare earth minerals. Keywords: small deposits, rare earths, rare metals, pegmatite, Nb-Ta, xenotime, India

Sep 1, 2012

By E. V. Zelinskaya, A. E. Burdonov

"In the raw aluminum production processon electrolyzers with self-baking anodes, during technological operations, flow-regulated treatment and adjustment of the electrolyte chemical composition produced by diesel and floor-rail technology, alumina and fluoride salts are spilled through the ventilation grilles of the electrolysis body aeration channels, leakage in the equipment, machinery and motorized machinery construction elements. As a result of this, a part of the bus station and the level of ± 0 (the basement room with supporting curbstones and columns, on which electrolyzers are installed) are covered with technological raw material. This leads to an increase in the conductor (bus) resistance, contact connections deterioration, cell insulation failure and raw materials loss. For example, at the enterprise ""Rusal-Bratsk"", as a result of the activity, up to 420 tons per month of alumina-containing wastes that are unfit for use in the electrolysis process are formed due to the alumina substantial contamination with salts of iron and silicon, which significantly reduces the technical and economic parameters of the electrolysis process. The main scientific problem is the processing (cleaning) of alumina-containing waste having a complex mineralogical composition of the material, its contrast and structure, from oxides of iron and silicon, using ""dry"" separation methods. In the performing the work process, qualitative indicators of the influence of external factors (air humidity, precipitation, sunlight, temperature difference) on the physicochemical processes components interaction during the raw materials storage are established. On the basis of laboratory tests, it is established that alumina-containing raw materials can be separated and photometric and gravitational separation methods used. A mathematical model of the motion of particles of primary and prepared alumina-containing raw materials in a cascade-gravity classifier was developed. The criteria and factors characterizing the alumina-containing material, as well as influencing and determining the maximum material enrichment, are established."

Jan 1, 2018

By J. P. Dai

The Fankou Mine in Guangdong province, China, processes a polymetallic ore containing averagely 4.2% Pb, 8.5% Zn, and 90 g/t Ag. The main metal minerals including sphalerite, galena and pyrite are very finely disseminated and unevenly occurred in the ore, making it difficult to liberate them from each other. This paper presents the processing technology of the Fankou plant and the characteristic features of the novel technology applied.

Jan 1, 2014

By D. Kosior

Influence of frothers (a-terpineol and n-octanol) concentration on kinetics of a three phase contact (TPC) formation by a bubble colliding with a hydrophobic surface (Teflon) of different roughness was studied using a high-speed camera (1040 frames per second). It was found that the Teflon surface roughness and the frother concentration strongly affected time of the TPC formation (tTPC) and time of drainage (tD) of the liquid film separating the colliding bubble from the solid surfaces. With increasing Teflon surface roughness, from ca 1 to 80 µm, the time of the TPC formation was shortened by over the order of magnitude, from ca 100 to a few milliseconds only. At low a-terpineol and n-octanol concentrations, thetTPC values were shorter than in distilled water due to lowering the bubble velocity in the frother presence and diminished bouncing of the colliding bubble. However, at high frothers concentrations the tTPC values were prolonged, despite that the bubble velocity was similar. The prolongation of the tTPC at high frother concentrations indicates that air (micro- and/or nano-bubbles) was present at the Teflon surfaces of different roughness. The mechanism of the tTPCprolongation at high frother dosage is described.

Sep 1, 2012

By Gabriela Pino, Maurício Torem, Diego Veneu

Because of its simplicity, economy and biocompatibility, research regarding the use of microorganism for decontaminating heavy metals produced by many industries is an area of growing interest. Also, there is a stringent need for the control of toxic metals produced during various production processes and released into the aqueous environment in order to avoid damage relevant to soil or groundwater contamination. Among the available treatment technologies, sorptive flotation has been considered as a promising alternative for the wastewater treatment. In the present study Streptomyces lunalinharesii strain was applied as bioreagent for the removal of copper, cadmium and zinc. The removal of those metal ions depends mainly on the respective pH value, influencing the aquatic speciation during the process, as well as the zeta potential of the system and biomass concentration. Langmuir and Freundlich isotherms have been depicted. Dispersed air flotation was applied as the subsequent separation method for harvesting the suspended metal laden microorganisms, following the biosorption of copper, zinc and cadmium. The investigated parameters (in batch mode, laboratory scale) were in this case the saturator pressure, the coagulant concentration and the recycled flow. Applying the optimum defined conditions, over 60% removal of metal ions have been achieved in one stage and simultaneously, quantitative separation of the used (metal-loaded) biomass has been obtained.

Jan 1, 2014

By B. A. Kutlin

29% of the total ore mined in the Russian Federation for copper production is finely disseminated copper-zinc-pyrite ores of the Ural Region. Physical and chemical characteristics of pyrite copper-zinc ores make for difficulties in obtaining high indices during processing. At present, the authors have elaborated the technology to improve the quality of copper concentrates up to 20.0% for the ones obtained during pyrite copper-zinc ore processing (based on the example of the ore mining and processing enterprise ?Uchalinsky GOK?, Russian Federation). There are examples of use of fair-sized pneumo-mechanical flotation machines by modernization of processing plants. Keywords: copper-zinc-pyrite ores, Ural region Russian, selective flotation, pneumo- mechanical flotation machines

Sep 1, 2012

By M. Barsky, E. Barsky

It is generally accepted that the optimal flow velocity for gravity classification is the final particle settling velocity or, which is the same, the particle spin velocity. However, we have found differences between the settling velocities and the spin velocities of the very same particles. Here we present the results of experiments in a cascading gravitational classifier comprising eleven stages. The feed material was introduced at each stage successively, from the first to the eleventh. The optimal flow velocity was determined for each case. From these experiments it follows that the value of the optimal flow velocity depends to a greater extent on the point of introduction of the feed (i.e., on the design of the device) than it does on the interaction between the solid phase and the flow.

Jan 1, 2003

By Wieslaw Wszolek, Kazimierz Trybalski, Ryszard Tadeusiewicz

"The present work is an attempt of neural networks application to the description of complex technological processes of useful minerals enrichment. Neural networks are among the most convenient tools that have been added recently to the professional toolbox of modelling specialists, and they are particularly useful in realisation of multiple practical tasks, characterised by great complexity and relatively low amount of available a priori knowledge about the nature of the modelled processes. They are successfully applied in a wide variety of problems related to data processing and analysis, their prediction, classification or process control. The object of the study was the technological site for copper ore enrichment by floatation, being a part of technological line in the Ore Enrichment Plant ZG „Polkowice”, KGHM „Polska Miedz” S.A.The main floatation is described by parameters measured by the supervision and control system, which can be grouped with respect to the functions performed for the object:a) input function: aFG - copper contents in the feed material for the main floatation [% Cu]b) control: LFG I - level in the first section of the floatation unit [%], LFG II - level in the second section of the flotation unit [%], LFG III - level in the third section of the floatation unit [%], LFG IV - level in the fourth section of the floatation machine [%]. These quantities compose the five elements long input vector.c) output function: ? - copper contents in the waste from main flotation (final waste) [% Cu]The measurement data, containing the above-mentioned parameters, have been collected during the normal operation of the plant. The data contain momentary values of the parameters, registered every 10 minutes, covering the period of 196 hours of the plant’s operation (1176 measurements for each quantity).For construction of the model used in the study classical multi-layer perceptron-type neural network has been used, with one hidden neuron layer, trained by the error back propagation method."

Jan 1, 2003

By Naoki Hiroyoshi, Hajime Miki, Tsuyoshi Hirajima, Masami Tsunekawa

Acidic solutions for chalcopyrite leaching contain cupric, ferrous and ferric ions, and the oxidizing power of the solutions is indicated by a redox potential, determined by the concentration ratio of ferric to ferrous ions. This paper reviews our previous studies on the redox potential dependence of chalcopyrite leaching in sulfuric acid solutions. Leaching and anodic-polarization experiments showed that coexistence of cupric and ferrous ions activate anodic dissolution of chalcopyrite, causing faster copper extraction at the potentials below a certain value (critical potential). The analysis of the AC impedance spectra for chalcopyrite electrode indicated that a high-resistance passive layer grows on the chalcopyrite surface without cupric and/or ferrous ions, and that coexistence of these ions causes a formation of another product layer and inhibits the passive layer growth at low potentials. These results are explained by a reaction model assuming the formation of intermediate Cu2S due to chalcopyrite reduction and the subsequent oxidation of the Cu2S. The critical potential corresponds to the redox potential of the Cu2S formation and the predicted values matched with the experimental results. Catalytic effect of silver ions on chalcopyrite leaching was also discussed based on experimental results and the above model.

Jan 1, 2003

By John A. Herbst, Ming Song, Xiangjun Qiu

It has been known for sometime that as wear occurs in tumbling mills there is an associated change in mill throughput. These changes have traditionally been simplistically, attributed to “mill volume effects”. New high fidelity simulation tools (involving DEM, CFD and Breakage models) are now giving new “microscale” insights into the complex interactions that occur between evolving lifter/liner profiles and breakage. The study described here shows that these new tools can allow the design of wear part profiles which will maximize mill productivity over the entire life of a liner/lifter system.

Jan 1, 2003

By G. Bulut

The aim of this study is to produce desiccant clay from a well known Ca-bentonite deposit in Turkey. Towards this aim, bentonite samples were first procured and then subjected to some characterization tests. Various methods were applied to enhance the moisture adsorption capacity of bentonites to a desirable level. These methods include utilization of some additives namely calcium chloride and heat treatment at various temperatures. It is shown that the moisture adsorption capacity Ca-bentonites without any additive are between 14%~17 % (w/w) upon by heat treatment whereas the addition of calcium chloride significantly, raised the moisture adsorption capacities.

Jan 1, 2014

By K. Amano, K. Haga, Y. Watanabe, A. Shibayama, A. Batnasan, A. Battsengel

"Apatite is an important host mineral in igneous and metamorphic rocks for production of phosphate fertilizers and phosphoric acid, and a potential source of rare earth elements (REE) production. For dissolution of REEs, sulfuric acid is better leaching reagent to develop the economical viable process for recovering of rare earth elements from apatite ore. However, the efficiency of rare earth elements dissolution in H2SO4 is about 30 % due to the formation of calcium phosphate or calcium sulfate as precipitate. On the other hands, phosphorus is mainly produced from phosphate ore. However, when treating rare earth elements containing phosphate ore, rare earth elements were discharged. Hence, development of novel apatite ore treatment process is required for effective utilization of natural resources. In this study, apatite deposit associated with REE was treated with sulfuric acid leaching and two stage precipitation by oxalic acid (C2H2O4) and magnesium chloride (MgCl2) for recovering REE and phosphorus, individually. Results showed that it can be seen the vast majority of La (87.5%), Ce (87.3 %), Pr (86.1 %), Nd (85.2 %) and Y (90.9 %) were dissolved in 1 mol/L diluted H2SO4 solution from the apatite ore. As average leaching rate of REE, over 85% of REE were leached by the condition. In the first stage precipitation using the obtained pregnant leach solution from leaching, over 90% of REE was precipitated by oxalic acid addition after controlling pH to 1 by NH4OH solution. After pH changed to 8.5, over 90% of phosphorus was recovered as precipitate by magnesium chloride addition in second stage precipitation"

Jan 1, 2018

By G. Y. Zhou

During Zijinshan copper heap bioleaching, pyrite was leached in plenty resulting in high ferric concentration in solution. It has affected bioleaching and extraction processing greatly. It results much acid and iron in solution and bad effect to extraction processing. The paper studied the influence factors in the course of pyrite leaching and ferric ion chemical oxidation, especially studied the redox potential for copper bioleaching so as to find key factors affecting the dissolution difference between chalcocite and pyrite. The results show that the redox potential is important factor. Copper and pyrite leaching rates are 95% and 11% respectively and there is great dissolution difference between them at redox potential 700 mV (SHE). During pyrite bioleaching, the indirect action of bacteria gives priority to bioleaching cooperating with the direct attack of microbial cells attached to the mineral surface. Redox potential is determined by ratio of ferric and ferrous, ferric in solution was supplied by the way of oxidation of T. f bacteria, sufficient bacteria concentration and active character were two vial factors of controlling redox potential. It is indicated that copper can be selectively bioleached during copper bioleaching by controlling redox potential of bioleaching. The conclusion will provide theoretic foundation on balance of acid and iron during bioleaching for copper of higher S/Cu ratio. The experinment proved that bacteria activation was decreased on condition of both low pH value and intermittent aeratation during bioleaching. It resulted that the oxidation velocity of ferrous ion was decreased and redox potential was controlled. The dissolution of pyrite was depressed. It would be possible to actualize selective leaching of secondary sulfide copper ore during bioleaching process.

Jan 1, 2014

By H. R. Manouchehri

"In mining and minerals industry, except profitability, there are some crucial factors that represent components in economic machinery of a mine and related activities. These are sustainability and minimizing environmental impact factor. Environmental concerns combined with the water and energy availability and related costs, as well as public license to operate all contrive to demand for more efforts targeting sustainability. Mining industry is highly energy-intensive (estimated to consume 6-7% of total world’s energy), with varying the energy efficiency across the industry resulting in significant costs. Size reduction is the main energy consumer contributing to almost 50% of the total energy used in mining. That means efforts must be made to introduce energy efficient comminution flow-sheets and machineries for sustainable development. Since the crushers are more energy efficient than mills, it is logic to push down-sizing in crushing stage(s) as far as technically possible. That has been strategy for Sandvik Mining and Rock Technology in supplying advanced and effective crushers to provide fine crushed product for subsequent milling stage. Lowering the energy consumption and related costs as well as increasing throughput have been the main objectives in design and development of comminution circuits and related machineries. Inefficiency in comminution technology, particularly in grinding, has long been regarded as a major area for investigation and development, especially when production of fines and ultra-fines are considered. In an attempt to explore the potential of fine crushing and its effects on subsequent milling process the fine crushing performance of Sandvik’s conventional cone crusher and Vertical Shaft Impactor (VSI) in pilot scale to define the energy consumption and circulating load in fine crushing. Tests were conducted to obtain fine crushed products at P = 2 mm in a close circuit. Furthermore, the crushed products were characterized and compared by grind-ability, morphology, and surface area measurement tests. Finally, the energy consumption to grind the crushed products to specific grind size was calculated."

Jan 1, 2018

By Ben Murphy, Alejandro Yanez, Tatu Miettinen

"Flotation using large volume cells has grown in importance during recent years, particularly given the increasing demand for minerals whilst ore grades are decreasing. Outotec introduced the TankCell® e300 in 2007 to enable concentrator plants to process these higher tonnages. From the beginning, TankCell® e300s with FloatForce® mixing mechanisms have demonstrated good metallurgical performance with decreased operating costs and high availability. This paper deals with specific engineering challenges that need to be considered when installing these units rather than giving examples of performance. Today there are over 100 TankCell® e300s operational worldwide. As more of these units are installed new technical challenges are encountered and solutions developed to maximize their productivity. Lessons have been learnt by operators, engineering companies and the cell manufacturers on how best to design and layout these cells in modern concentrators to ensure smooth transition from design to installation to operation. This paper presents information on important design considerations and learning that has been obtained through the design, installation and commissioning of the TankCell e300 around the world. Areas pertaining to cells layout such as feed and discharge arrangements along with items of metallurgical concern such as sampling, reagent addition and the potential benefits of installing a variable speed drive on the motor will be covered in depth."

Jan 1, 2014

By D. R. Nagaraj, Raymond Farinato

Water constitutes one of the most valuable resources employed in mineral recovery and processing. Identifying potential problems encountered in mineral processing in waters unusable for drinking or agriculture (including seawater and even hypersaline waters), understanding chemical factor interactions, and optimization of flotation reagents will greatly expand our ability to create more sustainable beneficiation technologies. The current paucity of our knowledgebase regarding high salinity effects on flotation clearly signals a need for a significant research effort. We report here results of a study designed to probe effects of pulp chemistry on metallurgical performance in the flotation of Cu and Cu-Mo ores in saline waters. The results clearly demonstrate that pH (more correctly dosage of pH modifier to target a pH set point) has the most significant effect on Mo recovery when using seawater. This is linked to the formation/precipitation of Mg(OH)2 when pH = 10.3 (in seawater). The type of pH modifier used, NaOH or Ca(OH)2, had no impact on Cu or Mo recovery, indicating that Ca2+ ions were not involved in any reduction in Mo recovery in the pH range of 9-11. Our results in tap water spiked with either Ca2+ or Mg2+ ions in the same pH range (controlled by NaOH), confirmed that Ca2+ ions had no effect on Cu or Mo recovery, but that addition of Mg2+ ions had a severe adverse effect on Mo recovery at pH = 9.5, and to a lesser extent on Cu recovery. The onset of Mg(OH)2 precipitation occurred at a higher pH, and the adverse impact of Mg(OH)2 on Cu recovery (and perhaps Mo recovery as well) was less, in sea water than in tap water spiked with Mg2+. These effects are attributed to the mitigating role of the high electrolyte concentration, notably NaCl.

Jan 1, 2014

By B. Z. Wu

The ore dressing of tin-polymetallic lean ores is a difficult problem and the research emphasis in domestic nonferrous metals mining field. Through research and tackle key problem,and in order to supply reference in dealing with the same types ores, this paper expatiates the exploiture and appli-cation of six item new technology and technics in ore dressing of tin-polymetallic lean ores. It include the technics of multi-step compounding disposing tailings, grinding step by step, grinding and processing circularly technology, high thickness without circle flotation technology, dispersedly flotation tin step by step technology, exceed fine lean plumbum stibium zinc flocculation flotation technology, the synthetically recovery of waste water after ore dressing technology.

Jan 1, 2014

By Sung. Hyejin, Kyoungkeun Yoo, Oh-hyeok Kown

The sediments near coasts and ports in Korea have been found to be contaminated with heavy metals and organic matters. So far the sediments have been dumped to landfill sites or ocean. However, the number of available landfill sites is decreasing and ocean disposal of wastes was strictly prohibited. Although physical separation processes have been found to be useful for the remediation of contaminated soil with heavy metals, because the sediments consist of fine particles, it is difficult to remove heavy metal component by physical separation processes. Furthermore, the sediments contain organic matter, so there is a concern about strong stink during the sediment treatment. The present study is aimed to develop the treatment process for removing heavy metals and organic matter from the contaminated sediments. The heavy metals and organic matter were oxidized and dissolved by electro-generated chlorine, and the chlorine used is regenerated and circulated in the leaching process. This system has economic and environmental advantages to reduce the wastewater and the oxidant consumption. The leaching results show that the metal removal efficiency increased to more than 99%, and more than 50% of organic matter was decomposed.

Jan 1, 2014

By B. McFadzean, J. Taguta

The enthalpy of immersion is the heat change arising from the replacement of the solid-gas interface with the solid-liquid interface when a solid surface is immersed in a liquid. Although immersion calorimetry has been established as a valuable and reliable means of determining solid surface properties such as wettability, it has seldom been applied in mineral processing research. In this study, precision solution calorimetry was employed to measure the enthalpies of immersion of different minerals in water. The enthalpies of immersion were then related to the first-order flotation rate constant as determined by the microflotation technique. The same measurements were also made on sulphide minerals whose surfaces were modified to different degrees of hydrophobicity using different percentage coverages of amyl xanthate collector. The enthalpy of immersion technique was capable of distinguishing and ranking minerals according to their wettability. All mineral types and collector-treated minerals conformed to the same relationship that was found between the enthalpy of immersion and the flotation rate constant. This conformed, empirically, to a power law equation. As the enthalpy of immersion decreased, there were large increases in flotation response for very small changes in hydrophobicity. In addition, a critical enthalpy of immersion (CEI) was found, above which no flotation could occur. The scatter in the data points could be corrected for by adjusting the rate constant using the density of the minerals to produce a robust relationship between the rate constant and enthalpy of immersion. These results have shown that the enthalpy of immersion is able to indicate both the natural mineral hydrophobicity and the extent to which collectors can render a mineral hydrophobic. This technique has considerable potential to be used as a sensitive and accurate measure of mineral surface wettability in order to predict flotation performance.

Jan 1, 2018

By M. Saba

In cyanide leaching procedure, achieving an acceptable efficiency for silver and gold is very time-consuming, thus, enough studies have not been performed for optimization and modeling of this process. The kinetics of cyanide leaching includes two steps: first step comprises a sharp slope while the other has a slight increasing trend. In the present study, in order to reduce the time and cost, the cyanide leaching process of a sulfide silver/gold ore was optimized in the first period. The applied parameters and their ranges are: temperature 20-40 (°C); time 1-8 (hrs); cyanide concentration 1-2 (mole cyanide / mole Cu); the percentage of solid to liquid 1-2 (%) and pH 10-12. For design of experiments fractional factorial 2(5-1) was used. Also four center points were applied to increase the accuracy of the model. In addition, by analysis of variance (ANOVA) the most effective parameters were identified and the optimized condition was determined. A regression model was proposed to describe the effects of independent variables and their interacting role on silver recovery. Results showed that the model was linear for silver and nonlinear for gold. In the gold recovery process, the two important parameters are time and pH with the former being more effective. Due to the existence of cyanide ions in the medium, temperature and cyanide concentration have less influence in the gold recovery process. Solid to liquid ratio, in addition, comprises a slight negative impact on the procedure. This emphasizes the different kinetics of silver/ gold cyanide leaching. Finally, using the optimum condition the amount of silver and gold obtained were 61% and 67% in 8 hours, respectively. While in general conditions, the results were 37% and 54% in 24 hours, respectively. Keywords: cyanide leaching, refractory gold/silver ore, modeling, optimization

Sep 1, 2012