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By A. R. Hasankhoei

Water recycling is of prime importance in mineral processing due to consumption of large amount of water. This issue is vital in areas with a low rainfall such as Shahre-Babak (Kerman, Iran). Deep cone thickeners, unlike conventional thickeners, have a low diameter to height ratio where large amounts of flocculants are used to increase particles settling rates. The high bed heights (over 10 m) produce enough pressure to create a paste type underflow indicating maximum water recovery. Flocculent preparation, conditioning, and distribution along with the bed height are among the important factors affecting the performance. Four deep cones are used to recover water from the tailings of the plant. Plant data indicated that the thickener never reached the target underflow percent solids (63%) and the average underflow concentrations were between 49 and 57%. By modification and optimization of flocculent preparation and distribution methods the underflow percent solids increased by 3-4%. This translated to an increase of water recovery from 67 to 73%. This was equivalent of 53000 m3 saving in monthly water consumption. Keywords: deep cone thickener, water recovery, flocculant, copper tailings

Sep 1, 2012

By H. Allenius

Today, most requests for quotations force all bidders to follow the bid document to the letter. The choice is then made based on price since it is the only difference in technically identical offers. However, clients allow and even encourage suppliers to come up with alternatives. Overall economy again, is much more than low investment costs. Operation costs may affect the economy of a project far more than a million saved in investment. There is almost always the choice: Should we go for the cheapest solution or should we go for the most economical solution? We strongly recommend the study of the long-term effects on investments as they often surpass any apparent savings in capital expenditure. With high operating costs, time is never on our side. Almost all relevant inputs and outputs in a concentrator have a value that can be expressed in a suitable currency. Unit prices may differ substantially from one operation to the other, but everything has a price tag and globalization has made it possible to move both goods and services to almost any place in the world. Even a rather simple exercise can give a good indication on which process improvements are worth pursuing when investing in new systems or equipment. The ones that do not qualify, as money earners, will naturally appear as clearly. No ?rocket science? is required, just process knowledge, practical experience, an open mind and some common sense and the reward may be the difference of having a good or an excellent project. The model we have developed can be made as detailed as required, but we do not recommend too much detail, as it sometimes tends to distract work and obscure the important issues. Two different process solutions compared in a simplified example illustrate the importance of evaluating a project based on its long-term effects rather than focusing on the investment costs only.

Jan 1, 2014

By A. Erdem

In this study, approximately 3 tons of coal sample taken from thickener entrance was prepared by mineral processing techniques and cleaned by gravity methods. The samples were classified to 5 size fractions by wet screening. The size fractions of +1mm and -1 +0.500 mm were chosen for direct consumption or cleaning by spirals. The studies by Multi Gravity Separator (MGS) were carried out with the -0.500 +0.280 mm and -0.280 +0.020 mm size fractions where the -0.020 mm fraction does not used in the experiments. The clean coal fractions of +1 mm and -1 +0.500 mm obtained by classification were subjected to lower calorific value (LCV), ash and total sulphur analyses. The results were 4168-4946 kcal/kg (on dry basis), 31.01-38.54 % ash and 4-4.27 % total sulphur content respectively. The results of the clean coal concentrated by MGS experiments in -0.500 +0.280 mm fraction was found 5918 kcal/kg LCV, 19.82 % ash content and 80.47 % combustible recovery. The results for the -0.280 +0.020mm fraction were 6004 kcal/kg LCV, 19.19 % ash content, 80.47 % combustible recovery respectively. With reference to the above experimental results, pre-economic evaluation studies were completed and decided to construct an additional unit to the plant. Capacity of the constructed unit is 75.000 t/y which corresponds $ 2.600.000 income in a year. General Directorate of Turkish Coal Enterprises concluded to apply this project to the other coal washing plants in the country due to the successful results of this study and laboratory studies has been going on by MTA currently. Keywords: coal tailings, mgs, recovery, washery, pre-economic evaluation

Sep 1, 2012

By V. F. Petrov

Today, sodium cyanide is extensively used for extracting gold, however it is highly toxic to the environment if not managed properly. This paper discusses the key challenges presented to gold operations in efforts to come into alignment with the Russian environmental regulations and suggests solutions to overcome these challenges. It is a fact that the major environmental threat cyanide poses to water sources. Therefore, natural water sources should be well protected from the adverse effect of cyanides used in hydrometallurgical processes. For this, the following site procedures and facilities are practiced: in-site and external water recycling systems, reclaim water treatment if required and tailings ponds with water impermeable screens (tailings ponds with controlled leakage). Cost comparison analysis of cyanide destruction methods was carried out. It was revealed that the aldehyde treatment method developed by Irgiredmet JSC demonstrated the best economics. Cyanide emissions are treated by mass-manufactured packed and membrane devices which allow to keep cyanides at the acceptable limiting values established by environmental regulatory agencies.

Jan 1, 2014

By V. Hema

Granular materials are widely used in process industries, such as chemical, pharmaceutical, cement, food, detergents, and fertilizers. Mixing, blending, calcining, reduction, heating, and granulation of these materials are frequently carried out in rotating cylinders. In all of these processes, the mixing and segregation of these granular materials is important as this controls the secondary phenomena in the rotating kiln such as heat transfer to the material. A significant amount of work is available in the literature but to date these efforts have not been able to capture the important parameters affecting the mixing and segregation in rotating kilns. In addition, the range of parameter values studied so far is rather limited. Simulations of granular materials are based on either discrete elements or continuum models. The discrete element methods (DEM) combine semi-empirical models for the inter particle interactions with the equations of motion from classical mechanics to simulate the explicit paths of all granules in a rotary kiln, thus yielding realistic predictions of the mixing process. This approach is very demanding computationally, which strongly limits the number of granules and the number of revolutions in a simulation. Continuum models dispense with the discrete particles and can therefore be scaled up more easily. But the constitutive relations that serve as the foundation for continuum modeling are difficult to come by, and often only applicable to specific systems and conditions. Here we have chosen DEM simulation for investigating the mixing and segregation behavior of granular materials in a rotating cylinder. This work is directed towards demonstrating the capability of the prediction of the mixing and segregation behavior of granular materials in a horizontal rotating cylinder through discrete element simulation. Further the effect of particle size and rotational velocity on the mixing and segregation behavior is investigated. The simulation results are quantified in terms of mixing index, mixing rate, segregation index and percolation index. Keywords: DEM simulation, granular mixing

Sep 1, 2012

By S. Gerl

Since Schönert, 1980 a multiplicity of scientists have dedicated themselves intensively to the scientific investigation of wet grinding in agitated media mills. The achieved research results led to a clearly improved understanding of the comminution mechanism in wet operated agitated media mills and in consequence also to clearly more efficient machines. In contrast to this the standard of knowledge on dry grinding in agitated media mills is still very small. The practical experience from numerous plants shows however that the transferability of knowledge from wet grinding to the dry grinding regarding transport phenomena and comminution behaviour, influence of the operating parameters and also wear is very limited. In the industrial application above all the continuous mode of operation is preferred. The main problem which has to be solved in agitated media mills is minor the comminution itself, than rather the question of the trouble free material supply and material extraction as well as the cooling of the mill. The agitated media mill MaxxMill® offers an innovative concept to overcome the feeding and extraction problem with its rotating grinding chamber, the eccentrically mounted agitators as well as the eccentric flow deflector with integrated material supply. Because of the pneumatic extraction of the ground materi-al cooling of the milling chamber is not necessary. On a MaxxMill ® laboratory mill with a 5 litre grinding chamber volume extensive parameter studies were carried out to study the influence of operating parameters on the continuous dry grinding of quartz sand. The test were performed in a continuous single pass operation without classification of the final product. Apart from the influence of the throughput rate on fineness above all the influence of the agitator and grinding chamber speed as well as the grinding media size was examined.

Jan 1, 2014

By L. Y. Wang

In order to produce the iron and steel products with high quality and decrease the output of steel tailings, the quality of molten iron is a critical factor for iron and steel companies, especially the content of sulfidic in molten iron. Hot metal pre-treatment, an important and effective method to desulphur, is widely used in steel production. Millions of tons of slag from desulphurization and slag skimming are produced each year in China, and many more times this amount is stored in slag dams because of the lack of effective means to deal with it. In order to achieve the goal of sustain-able development, recycling these slag becomes necessary. The main objective of this paper is to study the composition characteristics of slag that from desulphurization and slag skimming. The sample was obtained from Anshan Iron and Steel Group Corporation, processed by hot metal pre-treatment. In this study, the chemical components and the mineral compositions of sample were tested. The results of chemical components and iron chemistry phase analysis showed that the iron and sulphide content in this sample were high, and the iron products existed mainly in the form of magnetite, metallic iron, ferrosilite. X-ray diffraction (XRD) and scanning electron microscope (SEM) results indicated that the sample included metallic iron, ferrate, wustite, metasilicate, aluminate, aluminosilicate, white lime and soon. Grading magnetic separation test work showed that magnetic separation was an effective method to recovery iron products and decrease the sulphide content in concentrate, and the tailing could be used as the raw material or padding in cement production.

Jan 1, 2014

By K. Saberyan

In this study the extraction of zirconium and hafnium has been investigated by solvent extraction using Cyanex 302 in various media such as nitric, sulfuric and hydrochloric acid has been investigated. Effect of various parameters such as type and acid concentration, extractant concentration, type of diluent, equilibrium time, various foreign ions and finally type and concentration of strip-ping agent have been studied. The results showed that nitric acid was optimum media for extraction of zirconium and hafnium. The extraction of zirconium and hafnium occurred quantitatively in the concentration of higher than 4 M nitric acid but in hydrochloric acid media, quantitative extraction obtains over 8 M HCl. In sulfuric acid media, extraction of zirconium and hafnium is negligible. Stripping studies showed that the optimum reagent for stripping was 0.5M sulfuric acid.

Jan 1, 2014

By N. Kgabi, F. B. Waanders, E. Vinken, A. Mans

"Mössbauer and SEM identification of the iron mineral phases present in South African coal fractions from the Free State, Gauteng, Mmpumalanga, Natal and Waterberg coal fields, as well as from ash samples from coal used in the Lethabo power plant, containing a large amount of inorganic matter, was conducted. The iron is mainly associated with sulphur in the mineral but the amounts of these and other minerals vary considerably in coals from diverse origins. By means of Mössbauer analyses the iron bearing minerals were identified as pyrite, jarosite, illite and ankerite. In the SEM analyses quartz, associated with various clay minerals was identified with differences in abundance found between the coals from the different locations.The fly ash, produced at the high combustion temperatures in the power plant, gave rise to a spectrum, typical of a glass. SEM analyses showed that agglo- meration of the fly ash was due to the presence of Ca in the coal. The lab. produced fly ash was combusted at temperatures ranging from 200-1 200°C and the pyrite changed partially to hematite and partly into the glass due to the presence of the quarts and the clay minerals. A similar spectrum as the power plant fly ash spectrum was obtained.In the weathering experiments the pyrite changed to a sulphate component in a very short time during air drying."

Jan 1, 2003

By C. Han

The analytical results of Dagushan grinding workshop primary grinding operation product show that the size fraction of -0.079mm is 32.88%, the size fraction of -0.01mm is 9.97%, the rate of -0.01mm size fraction and -0.079mm size fraction is 30.32%. It means that there is too much -0.01mm size fraction in primary grinding operation product and fall out that there will not be a better result in following operations. Several tests have been carried out to control the size distributing of the primary grinding operation product according to confirm the appropriate conditions of grinding operation. Integrate with theoretic count, grinding property tests show that the appropriate rev ratio of ball mill should be between 85% and 90% so as to get better size distributing. Based on the results of grinding property tests, the shocking property tests simulated the momentum of different diameter steel balls in the ball mill have been carried out. It showed that if want to get better size distributing the appropriate diameter of steel ball should be 110mm. The tests result shows that regulate diameter of steel ball and rev ratio of ball mill could control the size distributing. Contrast to the technical parameters of ball mill in grinding operation now, there are some significant advices are given for practice and industrial tests.

Jan 1, 2014

By M. Wierink

The lifecycle of a resource, specifically a metal, is often depicted as circle from primary production from mining to minerals processing and via manufacturing and use to disposal and recycling. When a material is recycled, it is considered as saved energy compared to producing the material from primary source. This is, however, a simplified representation. At each step of the life cycle, there are changes in the quality of the material due to different materials chemical and physical interaction, phase transformations due to diffusion, radiation etc. Due to these physical and chemical phenomena there are losses of material, which as determined by thermodynamics are not recoverable within the life cycle. This can be considered as an increase embodied energy per mass unit of substance and loss exergy from the material cycle. With low cyclic loss, the material will remain in the recycling loop for a long time, while with high cyclic loss it will disappear fast. Where you put the material determines how fast it disappears from the resource cycle. In this research paper the phenomena of quality degradation of material and idea of increase of embodied energy and exergy loss within a resource cycles is portrayed. The cyclic nature of material states and transitions and energy consequences of material quality degradation as well as the parameters affecting the length of the time scales of the material cycles are described. Currently the cyclic embedded energy and the history of material is not taken under consideration in generic life cycle assessment. This easily results into a conclusion that lifetime of product is optimized only in terms of how much energy an appliance uses during its lifetime, while ignoring the loss of embedded energy due to the effects caused by the environs the material is subjected to during the cycle. Better description of the time properties of material give us a possibility to design toward optimum lifetime of products in terms of resource efficiency. Keywords: product lifetime, material lifetime, recycling, cyclic resource efficiency, material state, material quality, exergy, embodied energy

Sep 1, 2012

By Smuts. E. M.

This paper describes a methodology used to develop a numerical model for the study of particulate suspension rheology. Initially, Computational Fluid Dynamics (CFD) models of different rheometer geometries were tested with both a Newtonian fluid (water), and a non-Newtonian Herschel-Bulkley slurry. Rheograms were reproduced from these models and compared to experimental values. Once a single-phase model had been validated, a coupled model combining CFD and the Discrete Element Method (DEM) was created. Two open source software packages were chosen. CFD is implemented using Open FOAM®, and DEM using LIGGGHTS. These two different codes were coupled via another program called CFDEM. This coupled model is currently capable of modeling spherical particles in a suspending liquid. DLVO forces have been included in some models to account for inter-particle forces due to the surface charge on the particles. The coupled model is currently being validated. Preliminary results show good qualitative behavior of the model. Keywords: rheology, cfd, dem, suspensions, modeling

Sep 1, 2012

By B. McFadzean

Thiol collector mixtures are commonly used in the flotation of base metal sulfides and platinum-bearing ores. There are synergistic benefits claimed for these collector mixtures, with mixtures lowering total dosage requirements, improving coarse particle recovery and the rate of flotation. Some of the secondary collectors are known to have frothing effects. Therefore, a previous study aimed to decouple froth and pulp effects and considered only the bubble-particle attachments in the pulp. This was achieved through microflotation experiments, where various ratios of the ethyl and isobutyl chain lengths of xanthates, dithiocarbamates and dithiophosphates were used as collectors. Results from these experiments showed a marked increase in galena recovery using mixtures of xanthate with either dithiophosphate or dithiocarbamate. In the current study, the froth phase was introduced in the form of batch flotation studies to determine whether benefits noted during microflotation experiments would be carried through to a more realistic froth flotation scenario. The findings show that there was no significant difference in the flotation recovery between the best single collectors and mixtures of these collectors. In addition, single collectors that behaved poorly in microflotation experiments showed good flotation performance in the batch flotation experiments. The differences between the microflotation results and the batch flotation results are attributed to differences in particle froth stabilizing properties and/or differences in energy input between the microflotation and batch flotation cells. In addition, galena and pyrite showed marked differences in frothing effects and in their preferences for collector type. Keywords: froth flotation, collector mixtures, sulphide minerals

Sep 1, 2012

By Kazutoshi Haga, Ryo Kawarabuki, Atsushi Shibayama, Masato Kosugi, Masanobu Kawata, Refilwe S. Magwaneng, Kohei Mitsuhashi, Altansukh Batnasan

"The recovery of copper and iron from carbonaceous sulfide ore is of economic and environmental interest despite its processing difficulty. Hydrometallurgical methods can be used to concentrate sulfide metals of these hard-to treat ores in a simple and eco-friendly manner. In this study, high pressure acid leaching process was comprehensively studied to dissolve metals from an ore with organic carbon and carbonaceous gangue material using autoclave equipment. The sample used for the experiment was reduced to an average particle size of 75 µm after undergoing flotation to reduce carbonaceous gangue minerals. A comparative study on two leaching reagents of sulfuric acid and iron sulfate and their dosage was used to observe dissolution of copper and iron. Other parameters of temperature (90-170 0C), solid-liquid ratio (1:10, 1:5, 1:3 and 1:1) were investigated through kinetic studies to access the influence of organic carbon and carbonaceous material on recovery of copper and iron. Materials balancing analysis was used to evaluate the efficiency of metal dissolution. The effects of parameters on leaching rate and concentration was demonstrated. Results obtained from the experiment indicated low concentrations of copper and iron in pregnant leached solutions, which was attributed to acid consumption by organic carbon and carbonaceous material in feed. However, the high efficiency rates of 92.4% and 86.3 % for copper and iron respectively in sulfuric acid can be concluded that leaching of concentrates of carbonaceous ore is possible provided system control on type of acid, pH and temperature. The purpose of this research is important in understanding mechanism involved in dissolution of copper and iron in concentrates of carbonaceous ore and marks an improvement in leaching of highly contaminated ores."

Jan 1, 2018

By Leming Ou, Longsheng Yi, Qiming Feng, Yiping Lu, Qing Shi, Kun Liu, Guofan Zhang, Yanfei Chen

"Three important components of stirred tanks involved in energy consumption, the impellers and baffles, were investigated to intensify the agitation pretreatment on the flotation of nickel ores. Flotation tests revealed that the stirred tanks with two impellers had an advantage over those with one impeller in intensifying agitation pretreatment, and the higher agitation speed led to better flotation performance of nickel ores. Installation and removal of baffles were also employed in the stirred tanks, and flotation tests demonstrated that with baffles, the flotation grade increased significantly. These agitator design improvements were used to demonstrate that the energy supplied to the system significantly influences the flotation recovery and that if the energy consumption of the agitation pretreatment is ideal, flotation efficiency can be improved. Data from full-scale operations backed up these results.INTRODUCTIONThe flotation recovery of nickel-copper sulphide ore at the Western China nickel mine has historically been difficult due to the presence of large amounts of serpentine minerals (Feng, et al., 2012). Many studies reported that serpentine minerals tend to have a positive potential at pH values up to 9.5, while sulphides (such as pentlandite and chalcopyrite) have a low isoelectric point(Feng, et al., 2012). Serpentine minerals can form surface coatings on negatively charged sulphides surface due to electrostatic attraction when they interact with each other, which may also reduce collector adsorption and increase the hydrophilicity of the sulphide particles. In order to improve the flotation of nickel sulphides, sodium hexametaphosphate, sodium silicate, carboxymethyl cellulose (CMC), and other agents are used to disperse serpentine coating from sulphide surfaces in the flotation of the Jinchuan deposit and other nickel ores in China ( Kirjavainen and Heiskanen, 2007; Lu, et al., 2011). However, it is difficult to improve of the sulphide flotation due to the high dosage and the lack of selectivity."

Jan 1, 2018

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 M. L. Wu

A moderately thermophilic acidophiles strain had been isolated from the bio-heap leaching plant in Zijinshan Copper Mine, and the identification based on the PCR-16S rRNA gene sequence homology analysis with morphologic and physiologic methods was conducted by polyphasic taxono-my and phylogeny research. The results show that the strain by depurated belongs to Acidthiobacillus genus and is considered as Acidthiobacillus albertensis.

Jan 1, 2014

By Z. Q. Zhang

The iron ore from Yichang in China assaying 41.64% Fe and 1.02% P is a low grade and high phosphorus oolitic hematite ore. The separation of iron minerals from gangue minerals in the ore by conventional processing techniques is ineffective owing to their close similar properties. The modification of iron minerals by microwave-assisted reduction was investigated in order to improve separability of the ore. The effects of microwave-assisted reduction on the subsequent low intensity magnetic separation and floatation were examined. The results show that the main factors affecting the reduction and separation process are grinding size, reduction temperature and reductant. Fine grinding of the microwave-treated ore to smaller than 0.074mm was found to be imperative due to the tiny dissemination characteristics of iron oxide minerals. After magnetizing reduction by microwave heating at 500?, the magnetic concentrate containing 58.36% Fe and 0.67% P can be obtained with the Fe recovery of 91.28%. Magnetizing reduction drops the floatability of iron oxide minerals, thus reverse flotation is fit for upgrading the magnetic concentrate to contain 62.13% Fe and 0.21% P with Fe recovery of 81.59%. Compared with present microwave-assisted reduction technique of carbon reductant, using a waste iron powder as reductant is a novel and effective technique without the green house effect caused by the release of CO and CO2. Waste iron powder with a faster response to microwave heating then coke and charcoal can be recovered by magnetic separation in a low cost and plays the role of reductant and microwave heating accelerator.

Jan 1, 2014

By Lei Wang, Qi Zheng, Xiao-kui Che

"The wastewater emitted by gold chemical industry contained vast of different heavy metal ion, such as Zn, Cu and Ni etc. Among them Zn is the main ion in the waste water which causes the serious environment pollution. A method of preparing a kind of resin which is used for the removal of Zn by magnetic adsorbent was developed and was applied in practice. This adsorbent is a chitosan made of a kind of Fe3O4-chitosan modified by epichlorohydrin. The adsorption capacity of the absorbent and it was concluded that under the laboratory conditions, the maximum adsorbing capacity of this adsorbent could be 287.58 mg/g. The absorbent was also applied in the wastewater emitted by a gold industry in Shandong province. Its performance was tested and the result showed that the concentration of Zn ion in the wastewater was reduced from 0.58 mg/L to 0.0174 mg/L. What is more, the adsorption rate could be more than 97% when the dosage was 100L/m3 after adsorbing for 1h. KEYWORDS Selective, preparation, laboratory experiments, industry experiment, comparation INTRODUCTION Currently, most gold chemistry use cyanide to leach gold ore. Many different metals participate to this reaction besides the gold ion in this processing, so that the composition of the water is very complex. The waste water emitted by gold chemistry industry contains large amount of heavy metals. Definitely, if it was discharged without any treatment, the water would threaten the environment. The recuperation of any ion in the water would mitigate the pollution. Ion exchange resin, which is an effective material to do the water treatment with low cost, became widely applicated in this field [Yu-jiao Wang,2013]. Different kinds of resin were developed and the influence factors such as pH, adsorption properties and selectivity for different ions were investigated [CA Cruz et al,2018; PawanKumar et al.2016; Y Zhang, et al,2010; and ShengingSun, Aiqin Wang, 2006;]. The waste water mentioned in this article has a high Zn concentration, so a magic resin for Zn adsorption selectively we designed was used to manage this water. And the recovery of Zn could not only contribute to pollution abatement but also a best way to settle a dispute to the short of Zn resource. So the article mainly describes the preparation and the application of a kind of magnetic adsorbent used for the removal of Zn both in laboratory and industry. The aim of this article is to compare the effect of this resin in industry and laboratory?"

Jan 1, 2018

By M. Kargar Razi

According to the unique properties and many applications of nano silver powder, it was prepared from acid leaching tail solution. The low value residual gold and silver ions were occurred with fellow heavy metals as pollutants (Fe2+, Cu 2+and Zn2+) in acid leaching tail solution in Mouteh gold mine in Iran. Preparation of nano silver particles was achieved in two steps: first, by addition of ammonia as separation step and second by using different reagents as precipitation and extraction steps. Different controlled parameters were including pH, residence time and temperature, mixing time, and reducing reagents to metals molar ratio. Acid leaching process was carried out with sulphuric and nitric acid via suitable reductants. In order to remove copper, zinc, and silver ions from solution, all of the conditions were controlled. The optimum conditions for preparation of nano silver powder with less than 90 nm were pH 10.5, hydrazine/methanol to silver molar ratio of 3 to 4, and reduction time of 5 min in 45 °C. The results were evaluated via SEM, A.A and UV- Vis spectroscopy analytical methods.

Jan 1, 2014