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By E. V. Bratygin, S. P. Elnikova

"In the article carrying out technique of experiments for estimation of power efficiency of process of crushing in cone crushers «in a layer». The conformity of the granulometric characteristics of the crushed products obtained as a result of the tests, the theoretical equations for the size characteristics, and the choice of the optimal equation for the prediction of the granulometric characteristics of the final products obtained by crushing ""in a layer"". Optimization of granulometric composition of power of crushers working ""in a layer"" is carried out with the purpose of reduction of the electric power consumption at reception of a product of required quality. As a result of the experiments, dependencies are obtained, the relevance and applicability of the crushing process ""in the layer"" for obtaining crushed stone of improved quality is proved. INTRODUCTION A number of equations have been proposed for calculating the breakage energy. These include equations by Kirpichev and Kick, Rittinger and Bond (Bogdanov, Olevsky, 1982). Another equation for calculating the specific breakage work in breakage by impact and in stratum was proposed by Devyatkin (Boiko, 2003). In these equations, the breakage energy is proportional to the particle size raised to some power. In the equation proposed by Devyatkin, the ore piece thickness or the feed average diameter is used. The relationship between energy and breakage can be expressed as an equation (Lynch, 1981; Tikhonov, no. 3, 2008) where k is a coefficient characterizing the energy parameter depending on the strength of the feed, l is size in microns. The Rittinger formula is obtained for n = 2, the Kirpichev-Kick formula for n = 1, the Bond formula for n = 1.5. For n = 3 or higher, the equation describes fine and ultrafine grinding. R. Hookey proposed a formula (Lynch, 1981, Tikhonov, no. 3, 2008), where the size exponent n is substituted by a size function In all of the above equations, a single value of the feed and product size is used; for example, in the Bond equation, size is defined as the particle size of the 20% oversize (P80 and F80). However, a single size value can represent multiple distributions, making that the Bond method inappropriate for determining the size (Lynch, 1981). Describing an equation for estimating the grinding energy will allow to design the electric drive and ore preparation circuit for the given breakage method."

Jan 1, 2018

By Michel Brissette, Shaheer Sanuri, Veroljub Mihajlovic

"The main purpose of geometallurgy is to improve the mine planning by mapping hardness and throughput into the mine block model using geostatistics to eliminate the large production fluctuations caused by the ore hardness variability coming from different parts of the pit. However, not all grinding testwork available commercially can be applied to geometallurgy because of large amount of sample required and the associated cost per test. Geometallurgy is now being used in designing grinding mill but as the mining project progress, the accuracy of engineering must improve from 30-35% during the scoping study to 10-15% at the bankable feasibility stage and less than 5% for Engineering Procurement and Construction Management. For SAG milling, the SAG Variability Test (SVT) is an abbreviated version of the standard SAGDesign test developed for this geometallurgical need. The same amount of ore than the original test is ground for three cycles into an open batch SAG test and then the SAG pinion energy is predicted to the standard end point of 80% passing 1.7 mm. For ball milling, a Bond Variability Test (BVT) was also developed using the SAG ground ore from the SVT. The Bond ball mill grindability (Gpb), corresponding to the average of the net grams per revolution from the last three cycles of the Bond test, is also predicted from the third cycle. The relative error for both the predicted SAG ore hardness (WSVT) and Bond Work Index on SAG Variability ground ore (Sv-BVI), in kWh/t, averaged 5.5% and 3.8% respectively compared to the SAGDesign testwork values and are within 7% and 10% respectively from plant benchmark and within 7% from the samples sent to all partner laboratories. Both tests can be continued to measure the true hardness necessary for mill sizing. This article discusses the development of these two new tests, SVT and BVT, their potential use and accuracies in any geometallurgical program."

Jan 1, 2014

By Fatemeh Saeidi, Malcolm S. Powell, Mohsen Yahyaei

In order to deal with the problems of existing comminution models a new approach towards the development of mechanistic models has been made so as to better understand the physics of milling processes and environments. Despite enormous improvement in this field a comprehensive study of rock breakage characterisation, appropriate for use in these types of models, is still scarce. This paper reviews the existing models of comminution according to ore characterisation techniques and parameters. The authors have looked into the existing testing methods and their applied mechanisms of breakage, using standard test results available at the JKMRC. The study includes classifying testing devices such as the drop weight tester, rotary breakage tester, slow compression, and piston and die based on the few major fundamental mechanisms of breakage that are experienced by rocks in the breakage process. The paper compares the range of particle size and energy utilisation, applied strain rates and loading mechanisms for the equipment. The product size distributions from the various equipment is compared for equivalent input energies, various loading rates but the same level of energy intensity, a broad range of energy including low energy utilisation and fines generation rate for equivalent specific energy input. The results clearly show that the outcomes and conclusions on competence and energy for breakage are a function of the test method that is applied. In ongoing work, it is proposed to investigate common tests that can be applied to characterising ores in a manner suited to modelling a range of comminution devices.

Jan 1, 2014

By A. F. Usov

The paper is concerned with an analysis of the experience gained in development of special electro-technical installations applied in electric-pulse destruction of materials. A principle scheme of an electric electric-pulse installation is given, and electric circuit variants of its blocks made on various element bases are discussed. Also assessed are some ideas to further improve the technical and economic characteristics of the equipment.

Jan 1, 2014

By Dilip. Makhija, Asim. K. Mukherjee, Tamal Ghosh, Abhay Patra

In India around 15-20% of Run of Mine (ROM) from any iron ore deposit reports to slime dams as byproduct of iron ore beneficiation process. The proportion of iron ore slime to ROM will increase in future with higher proportion of lean grade ores in ROM. Furthermore, tonnages of iron ore slime will also increase with increasing demand of iron concentrate. Presently, this slime is stored in the dam in the absence of beneficiation technology. A beneficiation flowsheet has been developed at Tata Steel. This process produced concentrate of 2.2% alumina with 40 % yield from slime of 7-9% alumina. The iron content in the reject will be less than 40% thus adhering to the regulatory norm. Pilot scale study show waste from slime beneficiation is a good raw material for making a variety of building materials. Waste from slime beneficiation also has soil amendment properties. Pilot scale studies show productivity of rice increased when the waste of slime beneficiation process is mixed with soil. On commercialization of this zero waste technology slime generated from the iron ore washing plant will be completely used. In this paper the result of the pilot scale studies on slime beneficiation and utilization processes towards soil making and making of building materials are discussed in detail.

Jan 1, 2014

By Gülay Bulut, Ünzile Yenial

"Water composition has a significant effect on flotation. A better understand the role of water composition in flotation is very important for process quality and performance. Based on source of process water, the concentrations of the dissolved ions, hardness, contaminants and residual composition of reagents can varied in the process water. The various water resources employed during lead and zinc flotation caused activation, depression or selectivity effects on minerals due to the presence of different ions in solution. Metal ions in these water resources were adsorbed on the ore, whilst ions associated with gangue minerals were released into the flotation pulp.This paper includes a research for the effect of different water compositions on lead and zinc sulphide flotation. Experiments were carried out five types of water such as tap water, recycling water, tailing dam water, underground mine water and sea water. The ore sample was obtained from Esan Balikesir-Balya mine. The mineralogical study of ore sample shows that it contains mainly galena, sphalerite, pyrite, hematite, quartz, diopside, epidote, calcite, and chlorite. It is found that recycling water and tailing dam water has a positive effect on recovery of lead and zinc minerals and detrimental effect on content of both minerals. This result may explain with remaining reagents in these waters. Underground mine water and tap water gave nearly the same recoveries of zinc. Sea water affects the recovery lead and zinc negatively."

Jan 1, 2014

By K. V. Fedotov, E. V. Zelinskaya, O. V. Ulanova

"Mining enterprises, in particular, those on the territory of the Siberian platform, produce large amounts of pumped water, which cannot be recycled because of its high mineralization and, thus, is discharged as liquid waste either back into the ground or onto the surface. However, groundwater is often a valuable raw material and a source of useful chemical substances. Brines are unique groundwaters. In the current environmental and economic situation, the huge loss of natural raw materials and their deliberate conversion into wastes is unaffordable. The exploration of non-traditional sources of minerals such as the hydromineral resources (including pit water) is a matter of rational nature management. The industrial value of brines of the Siberian platform is due to the high contents of rare alkali and earth alkaline elements (lithium, rubidium, cesium, strontium, bromine, etc.). The absolute concentrations of these elements in brines are tens of times higher than the lower limits of the mining cut-off. The long-term data analysis was performed to estimate the environmental impact of liquid waste from two mining enterprises, namely, Korshunovskii (Irkutsk region) and Udachnaya (Southern Yakutia). The study was focused on the prospects of hydromineral resources as non-traditional sources of valuable elements and the exploration of technological processes for the selective extraction of rare alkali and earth alkaline metals from natural multi-component brines aimed at decreasing their negative environmental impact. The environmental and economic efficiency was proved for the processing of complex brines and the integrated selective extraction of rare earth metals from sodium chloride brines of the Korshunovskii plant and calcium chloride brines of the Udachnaya plant based on the ion exchange sorption, eluent chromatography, flotation, crystallization, and freezing techniques. The basic technological schemes were developed for the metal extraction from pit water and brines.INTRODUCTION In the Irkutsk region (the Angara–Lena artesian basin) and in Yakutia (the Olenek and Tunguska artesian basins), several mineral deposits are developed and, incidentally, aquifers bearing brines of different types are opened, which are eventually converted into liquid production waste (Rusetskaya et al., 1994) This raises the issue of the burial or utilization of brines since their use within the water circulation is impracticable under the existing technological conditions while their discharge into the surface watercourse is unacceptable because of the harmful environmental impact."

Jan 1, 2018

By Nicolus Rotich, Ritva Tuunila, Louhi-Kultanen. Marjatta

Most minerals, their ores, and gangue require sorting in order to maximize the recovery of the primary product during concentration. Gravity separation though old, is not obsolete and is continually playing an important role in mineral processing and many other industries, especially where plant energy efficiency is of concern. Screen designs e.g. material of construction, deck angle of inclination, the feed throughput, and physical as well as chemical properties of the particles, are critical factors to consider when using gravity for solid separation. Solids loading and screen geometry are significant, and easily manipulated operational parameters that affect both the screening rate and efficiency to a large extent. In this paper we applied nonlinear least squares optimization technique, and response surface methodology first, to assess the significance of the two factors, and secondly to select the best mathematical models that optimize both capacity and efficiency of the screening process. Initial experiments and confirmation tests were conducted on a prototype screen of 846.51cm2 effective area, (2100 cm2 total area). For glass beads of sizes 0.75-3mm, with feed loads of 10g up to 160g, and inclination angles from 5-20o, a maximum efficiency of 66.7%, and a screening rate of 22g/s was achieved with a screen loading of 86.5g, and an inclination angle of 12.43o. These results were then subjected to nonlinear least squares optimization, in which afterwards an optimum theoretical efficiency of 72% and screening rate of 31.2g/s were achieved at a loading of up to 104g. There was excellent performance at angles 12.5=?=17.5, but poor at the angles outside this range. The screening efficiency did not seem to respond significantly to changes in screen loading. Confirmation tests conducted at selected optimum parameters achieved an efficiency of 72.1% (at 17.5o with 88g load), and a rate of 27g/s at 16.5o with 104g.

Jan 1, 2014

By I. A. Podkamennyi, O. E. Kovalchuk, G. P. Dvoychenkova

"Using the methods of electron microscopy and IR spectroscopy, mineral components in the run-of-mine kimberlites and on the surface of diamonds were identified. The mechanism and sequence of mineral formation on the surface of diamond crystals were established. Systematization and classification thereof were undertaken for the first time ever.INTRODUCTION The high content of diamonds sized -5 mm in the kimberlite ores of Western Yakutia determines their processing depth in the size class 0.5 mm and finer [1, 2]. These diamonds are recovered by grease and froth separation based on the natural hydrophobic properties of the crystals. When refractory altered kimberlite ores are fed into the industrial process, the performance of grease and froth separation of the diamond ore greatly deteriorates. [4, 10, 15, 17]. Altered kimberlites are known to contain up to 90% of secondary minerals. This reduces by up to 40% the recovery of diamonds by grease and froth separation. [6].Diamond crystals from the grease and froth separation tailings were investigated. On the surface of the examined diamonds, hydrophilic mineral formations were identified, responsible for reduced recovery by physicochemical separation methods [3, 12, 18]. The aim of this study was to identify and describe the relationship between the composition of kimberlite ores and mineral formations on the surface of diamond crystals in order to systematize, classify, and then develop methods of removal in grease and froth separation processes. MATERIALS Following materials were examined in this study: - kimberlites of various material composition, - resulting slimes, - diamond crystals from kimberlite ore processing products."

Jan 1, 2018

By Henrique Kahn, Daniel Uliana, Carina Ulsen, Guilherme Nery

"Gold has been a material in high demand since the dawn of humanity. After hundreds of years of exploitation, the increasingly search for gold occurs in lower grade deposits with greater extraction difficulty. Therefore, for maximum efficiency, deep knowledge of the characteristics of these minerals and their associations is crucial, which is acquired through an accurate and rigorous routine of process mineralogy and batch extraction tests. The industrial gold process extraction occurs by gravity concentration, sulphides flotation and cyanidation. For gravity concentration, it is fundamental to establish the proportion of free or coarse gold grains and its association to heavy minerals; regarding flotation, the most relevant data are the proportion of gold associated to sulphides and their liberation by the surface area; for cyanidation, it is crucial to evaluate gold accessibility and the kinetics of leaching. Thus, the characterization of gold associations and liberation is vital to establish the plant design, to optimize operating plants and to reduce gold losses. Our aim is the characterization of gold occurrence in low-grade Brazilian deposits with complex mineralogical assemblages to support processing flowchart definition and to predict metallurgical recoveries. Gold distribution in light and heavy minerals was evaluated by heavy liquid separation and the occurrence of gold in free or locked particles was carried out on heavy products by SEM-based automated image analysis using the MLA system. All the products of heavy liquid separation were cyanidated in head samples with different milling conditions to evaluate the reaction kinetics and maximum recovery."

Jan 1, 2014

By Ghislain Bournival, Cagri Emer, Seher Ata

"It is well known among flotation practitioners that the contact angle can be correlated with the amount of material recovered from feed by flotation. The contact angle of solids can easily be modified by the addition of a collector. However, some collectors also have frothing properties thus altering the solid and bubble surface properties simultaneously. To avoid this problem, a technique has previously been used in which silanol groups are attached to the surfaces of the particles, but this method has its own problems. In this work, silica particles with various surface hydrophobicities were prepared using an esterification process. By using alcohols with different hydrocarbon chain lengths, from 4 to 12 carbon atoms, surfaces with a wide range of contact angles could be prepared. The technique was used in the modification of silica particles that were tested in a fluidized bed flotation column, and a laboratory mechanical flotation cell. In parallel experiments, dodecylamine (DDA) was used as a collector. It was found that irrespective of the type of flotation machine and surface preparation method, there was a close correspondence between flotation recovery and the contact angle of the particles. The silanation process has known drawbacks relating to the presence of moisture during the reaction, and the stability of the silane coating after it is been prepared. Esterification does not suffer from these disadvantages. This work has shown that the esterification technique is a robust alternative method for preparing hydrophobic quartz surfaces."

Jan 1, 2014

By M. Ranjbar, M. Khosravi Rad, A. Tohry

"The filling degree is defined as the volume ratio of the load inside the mill, which determines the power drawn from the motor, as long as the filling degree is not more than the optimum level. As the filling degree increases beyond the optimum level, the impact energy inside the mill will decrease and as a consequent, the mill power output will also decrease. Therefore, the mill filling degree is a key parameter in evaluating the grinding circuit performance, as it determines the mill reaction to the input feed. Since this parameter has an impact on the mill capacity, measuring the mill load is vital for control and optimization of grinding process. As in Choghart Processing Plant no instrument is available to measure the AG mill filling degree, an empirical model based on the bearing-oil pressure is proposed. The AG mill filling degree was related to the differences between the average pressure of input and output bearings, the circulating load and power drawn. It was shown that a quadratic model could relate the mill filling to the above mentioned measurements. This model showed that when the power drawn and circulating load decreases the bearing-oil pressure needs to be checked. If the bearing-oil pressure increases the feed rate needs to be decreased and steel ball be charged to the mill to increase the grinding and prevent mill overloading. INTRODUCTION The feed quality (size and hardness) affects the grinding process in AG mills. Reducing the top feed size and increasing the ore hardness reduce the mill efficiency and increase the particles with critical dimensions inside the mill. These will result in increasing the mill filling degree and reducing the mill throughput and efficiency (Wills and Finch, 2015). The volume ratio of the load inside the mill is called filling degree, which determines the mill power drawn. It is believed that if more energy is mainly spent on grinding (Wills and Finch, 2015). Therefore the mill power draw is used as a mean to control the mill efficiency."

Jan 1, 2018

By Danuta Szyszka

This paper presents results of tests performed to determine minimum concentration of a surfactant used at which coalescence of air bubbles during flotation has low probability to occur. The measurements of the critical coalescence concentration, also known as CCC, were carried out in a device consisting of glass cell into which air was pumped by peristaltic pump through capillaries. The flotation foam was recorded with a high resolution digital camera. Basing on the video records, average diameters of the air bubbles were measured and the values obtained were subsequently used to determine the CCC values. The author of paper determined the CCC values of surfactants tested using the linear regression method, and subsequently analyzed the results obtained. To define initially the capability of a tested surfactant to flotation, efficiency of multiparticle model flotation and flotation of individual size fractions were determined in a flotation apparatus for laboratory use in the presence of only foam making agent at CCC value pre-determined during the tests previously carried out. The tests of coalescence phenomenon were carried out with use of selected flotation frothing agents.

Jan 1, 2014

By A. N. Zagorodnyaya, Ye. G. Bochevskaya, E. A. Sargelova, Z. S. Abisheva, A. S. Sharipova

"In Kazakhstan, there is a unique sulphide copper deposit, in the ores containing the natural isotope of osmium-187 (more than 90 %). In the pyrometallurgical processing of concentrates for the target metal, osmium is mainly sublimated, with wet cleaning of metallurgical gases (dust and gas mixture) 40 % of it together with rhenium passes into washing solutions (wash acid). On the basis of this acid, the production of ammonium perrhenate was organized at the enterprise of the RSE ""Zhezkazganredmet"" and for the first time in the world practice - the isotope of osmium-187. However, the degree of its recovery from solutions does not exceed 8 % of the amount supplied with the charge or 25 % of the amount that was received for extraction. But the bulk of it (~ 75 %) remains in the raffinate, discharged to sewage treatment plants (wastewater). The studies presented in this work are aimed at solving the problem of osmium isotope-187 extracting from wastewater, which are a potential source of increasing metal production in Kazakhstan. The aim of this work is the development and scientific justification of osmium deposition regimes from wastewater using such reagents as thiosulfate and sodium sulphide. The influence of various physicochemical factors on the precipitation of the osmium was studied and optimal conditions for its maximum transition to sediment were chosen. An original method for obtaining osmium concentrate in the presence of sodium thiosulfate with the addition of potassium iodide from a new type of wastewater - man-made ammonia solutions has been developed. These solutions were combined mother liquors of solid-phase stripping operations and dissolution of pulp of crude ammonium perrhenate. On the basis of the obtained results, a settling technology for extraction of the osmium from man-made ammonia rhenium-containing solutions was introduced at RSE ""Zhezkazganredmet"". It should be noted that the degree of extraction of osmium, depending on its concentration in solutions entering on the settlement, and taking into account the addition of sulfuric acid, will vary from 60 to 90 %. The recovery of osmium during the test period was 58 %."

Jan 1, 2018

By David I. Verrelli, Peter T. L. Koh

"Recent experimental measurements of induction time made by direct observation with the ‘Milli-Timer’ indicated that angular particles were able to attach much more rapidly than spherical particles. There was around a tenfold difference in the respective induction periods for particle-bubble attachment. For industrial application, a more holistic comparison is needed, with the induction period for attachment being just one input. Over the years, CSIRO has developed a CFD-flotation model that incorporates both rigorous hydrodynamics, to simulate real industrial cell geometries, and a detailed model of the embedded flotation process, in which the induction period is an important parameter. We conducted transient modelling of batch flotation. First, spherical particles were modelled, as a ‘baseline’, for different particle sizes and levels of hydrophobicity. In the second set of results, the induction period was decreased by a factor of up to ten, simulating flotation of angular particles. Flotation recovery was found to depend upon induction period in a complex manner. For highly hydrophobic or fine particles, the induction period for spheres was already so low that recovery was limited by other factors (e.g. bubble-particle collision frequency). Further decreases in induction period, as for angular particles, did not have a significant effect on recovery in these cases. By contrast, when weakly hydrophobic or coarse particles were modelled, the recovery was predicted to be greatly enhanced for angular particles, in comparison to spheres. For these particles the induction period was limiting recovery, so that the flotation rate constant could be improved directly by reducing the induction period. This is consistent with batch flotation experiments using Ballotini reported earlier. Therefore, when dealing with weakly hydrophobic particles or relatively large particles that are to be floated, an enhancement can be expected for more angular particle shapes. In such cases, judicious specification of the grinding circuit may improve the overall efficiency."

Jan 1, 2014

By N. ??dyanik, Z. Kugukaldinova, O. Mishurina, Y. Glazkova, E. Mullina

"This paper describes the process flow of a selective processing method for acidic mine waters formed in the copper sulfide industry and characterized by a high content of copper, iron, and manganese ions. The proposed method comprises a series of sequential processes: the 1st stage is the recovery of Cu2+ ions by precipitation, the 2nd stage is the recovery of Fe2+ and Fe3+ ions as a dispersed phase by acid-base precipitation, followed by recovery in the 3rd stage of Mn2+ ions by converting Mn2+ with an oxidizing agent into insoluble forms of manganese and subsequent recovery of the dispersed phase by electroflotation. The developed method was tested on the acidic tailing storage facility (TSF) water of a mining project in the Urals region. The practical results of the implementation of the developed method have shown that its implementation will allow to recover copper, iron, and manganese in the form of salable products with a simultaneous decrease in their concentrations in adjacent water bodies down to the applicable MPCs. The process is a simple one, does not require any sophisticated expensive equipment and can be implemented either as a standalone solution or as part of existing treatment facilities. INTRODUCTION As a result of unsustainable utilization of natural resources in Russia, only a small fraction is processed into commodity products, while the rest is systematically dumped as emissions, effluents, and other wastes, polluting the environment. By amount of waste and concentration of valuable components, those wastes can be classified as aqueous technogenic resources [1, 2]. Therefore, the development of processing methods for this mineral resource category is an urgent and priority task that will significantly improve the industry’s profitability and the environmental conditions in the respective regions. MATERIALS AND METHODS Following research methods were mainly applied in this study: lab-scale and pilot-scale tests in a diaphragmless two-chamber electric flotation cell; for solutions and recoverable process products — chemical analysis using photometric determination techniques for metal cations and atomic adsorption determination techniques for the processing products. The phase composition of the precipitates formed in the process was investigated by X-ray phase analysis in the general-purpose diffractometer with a copper anode DRON-1."

Jan 1, 2018

By Glasswell K. Nkonde, Fredrick Chileshe, Steven Simukanga

Improving food security by increasing crop output is a primary objective for most countries in the sub- Saharan region. Most soils in the region are deficient in phosphorus an important nutrient after nitrogen in plant growth. Phosphates are therefore used together with nitrogen and potassium based fertilizers in improving crop production. Zambia like many other countries in the sub-Saharan region imports phosphate fertilizers for use by its farmers. However, indigenous phosphate deposits of igneous origin exist in Zambia of which the main ones are Chilembwe in Petauke district, Mumbwa sugarloaf in Mumbwa district, and Nkombwa Hill in Isoka district. If commercially exploited, these deposits could become a ready source of inexpensive phosphate for the local farming communities in the country. Previous research has shown that partially acidulated phosphate rock (PAPR) produced using Chilembwe phosphate rock is just as agronomically effective as the imported superphosphate fertilizers on food crops in most of the Zambian soils. PAPR is produced by reacting finely ground phosphate rock with only a fraction (usually 50%) of the stoichiometric quantity of the sulphuric acid required to fully convert the apatite in the rock to monocalcium phosphate thus making the process cheaper in terms of acid consumption than the poduction of single superphosphate where the apatite in the rock has to be fully converted to monocalcium phophate. The factors that affect the percentage of available P2O5 in the PAPR produced include particle size of phosphate rock, degree of acidulation, concentration of acid, process temperature profile, residence time and drying temperature. These factors were studied in a 25kg/hr PAPR pilot-plant in the School of Mines at the University of Zambia using Chilembwe phosphate rock. The PAPR pilot-plant consisted of a rotary drum granulator as the main reactor, a rotary drum dryer and a triple deck vibrating screen. Ground phosphate rock was reacted with sulphuric acid and water in the granulator to form a granular product which entered the drier. The dry product was screened into three size fractions. The 1 – 4 mm size fraction was the final product whilst the –1mm size fraction was recycled. The +4mm size fraction was sent to a crusher while the crushed PAPR was sent back to the screens.

Jan 1, 2003

By S. Banisi, E. Arghavani, M. Pourkani, M. J. Rajabi, Gh. A. Mohamadian, H. Bidshahri, Gh. A. Parsapour

The Sarcheshmeh copper complex flotation circuit of plant No.1 consists of two identical north and south sections where each includes four rougher (each bank consists of 14 cells), two cleaners (each bank consists of 8 cells), two recleaners (each bank consists of 2 cells), and two scavenger banks (each bank consists of 10 cells). The reduction of feed grade along with a change in the mineralogical composition is the main reason of current lower concentrate grade (24%) compared with the design concentrate grade (32%). Because of a lower feed grade, the amount of rougher concentrate has decreased which in turn has significantly reduced the feed rate to the cleaner, recleaner, and scavenger banks. This has increased the mean residence time of the material in the cleaner section resulting in a lower final concentrate grade. A laboratory study showed that the final concentrate grade can be increased by 2-4% if one cleaner stage is added to the flotation circuit. In this research, based on the laboratory results, one cleaning stage was added to the current flotation circuit. In order to make this modification instrumentally possible in the plant, the final concentrate was gravity transported to the Mo-Cu thickeners. This released 2 pumps and associated tanks which made addition of one cleaning stage practicable. Finally, a part of the cleaner and scavenger cells were used as the third cleaning stage. This decreased the residence time in the cleaner and scavenger banks. After implementation of one cleaning stage in the south section of the plant, the performance of the circuit compared with the identical north section. It was found that at the same recovery, the concentrate grade of the south section increased by 2.5%. The promising results led to the implementation of adding one cleaning stage in all sections of the flotation circuit.

Jan 1, 2018

By A. R. Videla, P. R. Brito-Parada, I. Mackay

"Linking results from laboratory scale experiments to industrial flotation behaviour is challenging. Typically, such experiments involve batch tests in which the system does not operate at steady-state, making it difficult to infer the effects that operating conditions have on flotation performance. In order to overcome this limitation a 4-litre recirculating tank was previously developed at Imperial College London. This tank is capable of reaching, and operating at, steady-state by recycling overflowing concentrate back into the feed. As well as instruments to control operating conditions, it is fitted with a system of sensors that allow the surface of the froth to be dynamically monitored. From this information, it is possible to measure the air recovery—a proxy for froth stability. Thus, this bench-scale tank can be used to understand the effect of differing operating conditions on flotation performance at steady state. However, so far, this cell has only been used to investigate idealised systems with only one or two species.Reprocessing of tailings dams is not only environmentally desirable but also increasingly economically feasible due to the declining head grades of primary deposits. There is also the added benefit of no further milling being required prior to flotation. However, the effects of fine and ultrafine particles on froth stability are not yet fully understood. In this work, the bench-scale continuous tank has been used for the first time to determine the flotation response of a complex feed, consisting of samples from a copper tailings dam, to changes in operating conditions. It was shown that the froth stability in the system is comparable to that of previous work and industrial tests, with a peak in air recovery being found at a superficial gas velocity of 1.13 cm/s. There is scope to optimize the froth stability of tailings flotation for enhanced metallurgical performance."

Jan 1, 2018

By Vladimir G. Kochnev

An innovative AG and SAG technology aimed to be applied in grinding of ores and in the production of construction materials is described. A novel design of a cantilever-type mill capable to operate in autogenous, semi-autogenous and ball grinding mode ensures easy delivery and installation even in remote areas, and low capital and operating costs. Results of the tests of the new heel-shaped liners performed by TTD jointly with ALROSA, MINTEK and Anglo-American Corporation are reported. The approach includes also a novel discharge grid design and a technique of treating the material of critical size. These innovations make grinding in AG and SAG mills dramatically more effective, with an increase in the throughput rate and a reduction in power consumption ranging from 1.5 to 2 times.

Jan 1, 2003