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By Luis Bergh, Francisco Díaz, Isabel Panire, Juan Yianatos, Luis Vinnett

"In this paper, industrial data of residence time distribution (RTD) in mechanical flotation cells is presented, which were measured in several plants using the radioactive tracer technique. Results include mechanical flotation cells of 100 - 300 m3, which were operated with effective residence times from 2 to 7 min. Tests were developed in forced air and self-aerated cells for liquid and solids (non-floatable) per size classes. Different RTD model structures including perfect mixer, Large and Small Tanks in Series (LSTS) and by-pass flow plus perfect mixer were evaluated and compared for single cells. The actual mixing regime was related to the effective residence times and cell designs based on the model fitting. By-pass flow percentages were typically lower than 10%, therefore the perfect mixer model plus a dead time was a suitable model structure in most cases. On the other hand, the arrangement of cells in series was effective in reducing the bypass flow observed in single cells (by-pass flow percentage greater than 5%). In addition, the N perfectly mixed reactor in series model was used to represent the mixing regime along flotation banks, which were operated with mean residence times in the range of 18 - 53 min. Results showed that N tanks in series plus dead time were closer to the actual values in most cases."

Jan 1, 2014

By Johan Nell, Paul den Hoed

"Carbochlorination tests were conducted with matched particle-size fractions of rutile, ilmenite and hightitania slag in a small bubbling fluidized-bed reactor. The effects of temperature, the type and proportion of solid reductant in the charge, and the fraction of Cl2 in the fluidizing gas were investigated. Tests confirm the need for solid carbon in the bed if chlorination is to run at high rates. With solid carbon in the bed, CO supplied with the fluidizing gas does not increase significantly the degree of chlorination after 75 minutes.When large proportions (30 wt%) of carbon are added to the charge, then the reactionTiO2 + 2C + 2Cl2 = TiCl4 + 2COis favoured overTiO2 + C + 2Cl2 = TiCl4 + CO2Ilmenite is chlorinated more quickly than titania slag, which in turn is chlorinated more quickly than rutile. Rates of chlorination at 1100°C and 1000°C are much the same and significantly higher than at 900°C. Chlorination is associated with significant increases in particle porosity (even for rutile), which is brought about by the rapid initial chlorination of FeO and MnO (in ilmenite and slag) and (it is argued) by the chlorination of Ti2O3 which forms at high-energy surface sites."

Jan 1, 2003

By Graeme Jameson

"In current flotation circuits it is customary to grind the whole of the mill feed to an initial size, which is determined by the liberation characteristics of the ore, and the ability of the flotation machines to float the fully liberated particles. Usually, the product of the primary mill will be ground further in a ball mill, to improve the liberation of the values and hence the product grade, before passing to rougher flotation cells. The final grind size is ore-dependent, and is a balance of factors including the relation between surface liberation and grind size, the grain size of the valuable particles within the host rock, and the feed grade. The P80 for the feed to flotation may be as high as 300 µm for free-milling copper ores, and as low as 53 µm for finely disseminated complex ores. The grinding of the feed ore requires considerable input of energy. The rate of replacement of wear components such as mill liners and media, is proportional to the energy input. The costs of these two factors - energy and wear - are usually comparable and together they form the major part of the running costs of a concentrator, and indeed, of the whole mining operation. The energy required increases as the final grind size decreases. This talk will focus on the reduction of milling costs that could be achieved, using a fluidized bed flotation technology that can give high recoveries at coarse particle sizes. A number of different circuit designs will be presented, using the new technology. Calculations show that reductions in the running costs of a mine and associated concentrator of the order of ten to twenty percent could be achieved."

Jan 1, 2014

By Slobodan B. Vujic

"For the requirements of the mining company “Rudnik-Rudnik”, engaged in undergr-ound exploitation of polymetallic ore and lead, zinc and copper concentrates production, the Department of Computer Application of the Faculty of Mining and Geology, University of Belgrade, designed a computer supported and integrated information-management system. This paper presents a concept of this system covering both monitoring and management of production in ""Rudnik-Rudnik"".The ""Rudnik"" Rudnik, Yugoslavia is a mining company, engaged in underground exploitation of polymetallic ore and production of ore, zinc and copper concentrate as well as other metals such as silver, bismuth and cadmium. This mining company runs stable business activities and undergoes a permanent growth of valuable production volume.The basic characteristics of production-technical system of ""Rudnik"" company are: uniform and up-todate technical-technological solutions: linking of production chain from underground exploitation of ore to flotation, namely final product - concentrate of lead, zinc and copper; complete mechanization of production; relatively low level of computer technics implementation; namely, ununiformed implementation of different application of computer-supported information technologies in production and business activities of the Company.These are the assumptions on the basis of which the management of the Company made a decision, in 1999, to upgrade information-management functions through development and application of modern integrated and computer-supported production-business information-management system (hereinafter: IMS, namely IMS Rudnik). For this purpose the Company requested the Department of Computer Application, Faculty of Mining and Geology, University of Belgrade to make the Project on IMS for their needs."

Jan 1, 2003

By I. V. Makarskii, D. N. Nikitin, L. G. Tarasova

"The extent and nature of the damage to diamonds at processing plant is largely determined by the design features of the equipment, the characteristics of the feed ore and the parameters of the ore disintegration process (change in the rotational speed of the autogenous mills, variations of the water supply to comminution process, choice of the optimum charge, etc.). To monitor the intactness of diamonds, an instrumental method using the X-ray tomography system and colored synthetic indicator diamonds was developed for identifying the process-related damage. The X-ray tomography system consists of a CT-Portable X-ray tomographic scanner, a crystal positioning device and customized software (developed by the Fraunhofer Institute and Aliud GmbH, Germany). The developed method enables improvement of the accuracy of the results, exclusion of the subjectivity of the mineralogical assessment, acceleration of data processing and promptly planning of the activities aimed at reducing the process-related damage to diamonds. KEYWORDS Diamonds, colored indicator diamonds, process-related damage, loss of mass, instrumental method, X-ray tomography system. INTRODUCTION Industrial tests of ore processing technology at the enterprises of ALROSA PJSC are accompanied by assessment of the process-related damage to diamonds. The assessment of the process-related damage to crystals is carried out for prompt elimination of factors contributing to the increase of impact forces in the process flow sheet of ore treatment plant. For this purpose a specially selected parcel of -4.0 + 2.0 mm sized natural indicator diamonds is used. The diamonds are exposed to ionizing radiation in order to turn them green and thus to create a distinctive feature. Colored natural indicator diamonds are described, photographed in several views and introduced into the process flow sheet of the processing plant, then extracted from the process flow, described and photographed again. The comparison of diamonds before and after their passing through the process flow sheet of the plant allows to find evidence of process-related impact on the crystal and to calculate the factor of process-related damage (the number of crystals damaged during liberation and recovery), the loss of crystal weight and the degree of damage to the crystals. The method of colored indicator diamonds is used to select processing methods, equipment or regime which would be the safest for diamonds based on the analysis of the factors of process-related damage. There are limitations of the method, such as:"

Jan 1, 2018

By Ronald Díaz

"Cerro Corona is a porphyry ore with different geometallurgical units and alterations produced by an extensive family of geological failures that have determined a special type of mineralization. With the increasing depth of the mine, it is estimated that the host rock will be less altered. Consequently, the ore will have a higher resistance to breakage accompanied by associated problems such as lower throughput. In light of this reality, various projects have been carried out with the objective to optimize mineral processing of ore with low clay content and high hardness, including reducing the blasting grid, increasing the load factor, using adequate mixtures of hard ore, reducing crusher settings, installing air guns in the transfer chutes, increasing ball charge, and changes in the lifter design, wear control in the hydrocyclones, syntonization of control logics, supervisor control of the SAG mil, characterization of feed ore, etc. However the most important factor was the teamwork between mine and plant personnel, aiming at common objectives for the company. These projects started in 2011, including characterization of mineralogical domains, breakage and blasting characteristics, and also a revision of the actual operating conditions in the crushing and grinding circuit. The development of different designs of the SAG mill lifters and the unloading grates, a 16% ball charge increase, improvements in the blasting process, reduction of the primary crusher setting, weight reduction on the feed lid, and variation of operational parameters, all allowed the company to achieve its objectives of maintaining impact control and steel recharge within the expected operational parameters. The achieved throughput is above design capacity, sustainable, and not without new challenges for maintaining and optimizing this production level."

Jan 1, 2014

By D. B. Sundar Ramam

In the recent past, a paradigm shift in terms of resource utilization and beneficiation practices is experienced by the Indian mining and mineral sector. Depleting iron ore reserves coupled with increasing demand for low-alumina iron ore fines to improve blast furnace performance in terms of productivity and reduced slag rate necessitate intensive beneficiation of iron ore. The task is even difficult for Indian iron ores, which are generally high in iron content and at the same time characterized by aluminous gangue. In 2006, M/s Tata Steel commissioned a state-of-the-art Jigging Plant (Batac Jig) at Noamundi Iron Mine (NIM), mainly to reduce alumina in iron ore fines. The jigging plant is incorporated in the existing beneficiation circuit to treat ?10+0.5mm size fraction of classifier fines. Over the course of plant stabilization while the plant could deliver desired ore upgradation and average product alumina, variability in terms of alumina content has been a concern. This paper discusses a case study of process parameters optimization in jigging operation to achieve consistent product quality while improving the effectiveness of gravity concentration for the beneficiation of Noamundi iron ore also to take care of inferior plant feed (input) grade year on year. The operating variables used to optimize jigging operations include bed height, pulsion and suction time, particle size, strokes, and plant throughput rate.

Sep 1, 2012

By Kilian Neubert, Hermann Wotruba, Henning Knapp

Sensor-based sorting has been integrated into more and more applications in mineral processing over the past decades. Various sensor types, such as line scan cameras, near infrared sensors and X-ray transmission sensors, allow the separation of a vast variety of raw materials. Sensor-based sorting has several economic benefits which can make the difference between an uneconomic operation and a profitable mine. Sensor-based sorters can be applied to fulfill various sorting tasks, such as waste rejection, product quality improvement and ore type diversion, and have a significant impact on the layout of the processing plant. Therefore, it is important to include sensor-based sorting into the planning of a processing plant at an early stage. To evaluate the applicability of sensor-based sorting for any specific ore type, it is currently necessary to provide several hundred kilograms of material for subsequent bulk tests. In exploration, ore samples are usually rare and only available in form of drill cores. The acquisition of drill cores is time-consuming and expensive especially for deposits in great depth. Hence, it is unfavorable to spoil valuable drill cores for bulk tests. This paper describes a methodology to evaluate the applicability of sensor-based sorting based on drill core analysis. That methodology offers the possibility to calculate the achievable performances of different sensor types for various grain sizes without comminution of drill cores. The general methodology is shown on basis of an exemplary test work on drill cores from a currently conducted exploration.

Jan 1, 2014

By P. Prakash

A dual-drive planetary mill, which has a rotating shaft that sweeps a circle of diameter 750 mm, has been designed. The planetary mill is powered by a 5 hp motor to rotate the main shaft and a 3 hp motor to rotate the jars. The charge dynamics inside the horizontal-axis planetary ball mill was established using three-dimensional DEM simulations. The simulation results provided data to determine the impact energy distribution and the effect of process parameters such as mill speed and filling. It has been observed that the mean impact energy per unit time increases with rotation-to-revolution ratio, whereas the average number of inter-particle impacts per unit time decreases. The mill was also used to synthesize a variety of powders. Here three case studies of reaction milling are briefly presented: (i) cementite and silicon carbide, (ii) oxide dispersed strengthened (ODS) steel, and (iii) magnetite from blue dust. In each case, the powder was produced by mixing and then milling the corresponding pure components. The phase evolution, particle size distribution, and morphology of particles during milling were studied for various samples collected at different milling times using laser size analyzer, SEM, TEM, and Mössbauerspectroscopy. The results established a convenient way to produce powders of high technological and commercial value.

Sep 1, 2012

By Verónica Fernández, Jaime Solari

"The Chilean Environmental Impact Assessment System (EIAS) of investment projects was created in 1994, date in which the General Environmental Law was enacted. The compulsory environmental approval of projects began in 1997 when the Regulation (S.D. 30/97) was officially issued. By beginning late to regulate the environmental effect of investment projects, Chile could take advantage of the international experience in the matter and therefore, the EIAS has many of the attributes of successful environmental assessment systems elsewhere. Thus, the main characteristics of the Chilean EIAS are: preventive, single-window, specific to certain projects, multi-agency assessment at the regional scale, 3 kind of applications, deadlines, citizen and native communities participation, link to relevant permits, definite conditions of approval/rejection, review of applications by an ad hoc institution. The Chilean EIAS has allowed during the period 1997-2013, the review of 21,110 projects for a total investment value of US$ 408 billion, of which a 76% have been approved. In the case of the mining projects, the corresponding figures for the similar period are 1,257 projects for a total investment value of US$ 119 billion, of which 78% projects were approved. The experience derived from the environmental impact assessment of mining projects indicates that Chile has been successful in linking together mining development with environmental protection. There is still little prejudice against mining and this is a still a largely welcome economic activity at all levels in the relevant regions of the country. The challenge that mining companies face today in Chile is to improve the sustainability of projects and operations, by learning to share scarce and valuable resources (water, glaciers, renewable energy) with the local and native communities, through a process of dialogue whereby mining development also generates benefits for these communities."

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 Sudhir Srivastava

India hosts a wide range of globally significant mineral resources, including four fuel minerals; 11 metallic minerals; 22 minor minerals and 52 non-metallic minerals. The country ranks among world?s top five nations for its commodity reserves of coal and iron ore. Interestingly, only small part of country's landmass has been explored that provides opportunity for future substantial mineral discoveries. India plans to double infrastructure investments to US$ 1trillion. Despite the challenges in infrastructure project implementation, mining sector remains a key driver of demand growth for commodities in the years to come with a good prospect to grow in future.

Sep 1, 2012

By Ming’an Wei, Chuanyao Sun, Yangge Zhu, Fayu He, Yanbo Shang, Xingrong Zhang

In order to discuss the separation mechanism of copper-molybdenum ore, surface electronic structures of chalcopyrite and molybdenite were studied in the paper, by using First Principles method of quantum chemistry. So, the separation mechanism of thioglycolic acid (TGA) with chalcopyrite and molybdenite was revealed better. The results showed that differences of the electronic structure of chalcopyrite and molybdenite could directly affect their interactions with TGA, such as band structure, density of states, Mulliken populations, and so on. And the frontier orbitals of chalcopyrite and molybdenite were also calculated by Dmol3 after the optimization by CASTEP, from which the interaction energies between minerals and TGA were obtained and compared. So, the essence of flotation separation of copper and molybdenum were well revealed.

Jan 1, 2014

By Gustav Hawlitschek, Henrique Kahn, Carina Ulsen, Renato Contessotto

"The problems related to waste dumping increased with the growth and development of large cities. In the U.K., more than 50% of landfill waste comes from construction use and the U.S. alone produces around 200 to 300 million tons of CDW annually. The exhaustion of natural sand deposits close to large urban centres stimulates the recycling of construction and demolition waste for the production of recycled aggregates as a construction material. This paper presents a flowchart for the production of recycled sand with low porosity and regular shape by the selective removal of the cement paste attached to recycled aggregates. The products characterization was carried out by the determination of the particle size and shape distribution, chemical and mineralogical composition, heavy liquid mineral separation and quantification of all present phases using a scanning electron microscopy with automated image analysis (SEM-MLA). The comminution of CDW by vertical shaft impact crusher made possible the production of a lower porosity recycled sand. The heavy liquid mineral separation showed that the proportion of low porous phases (d>2.5 g/cm3) is very high, exceeding 70% of the weight, encouraging further mineral processing separation to obtain a fine recycled aggregate with less cement paste content. The mineralogical characterization by XRD and SEM indicates that the main phases are tectosilicates, phyllosilicates and calcite which one can be attributed to both calcareous aggregate and cement paste. The precise quantification of cement paste and calcite/dolomite alone is just possible by automated image analysis. The characterization results demonstrated that proportion of phases with no cement paste attached increases progressively in denser products. The results of heavy liquid separations and image analysis are comparable and automated image analysis can be used for the characterization of phase content and their main associations."

Jan 1, 2014

By Zhou Yucai, Zhou Jing, Zhu Yimim

"In this article, research on the beneficiation process for a carbon containing copper-molybdenum deposit in Henan province has been carried out. The elemental composition, mineral composition and relative content, characteristics of embedded and symbiotic relationship, the forms of the copper-molybdenum particlesand their disseminated features, and particle size distribution have been worked out. Flotation behavior of copper-molybdenum mixed flotation and separate flotation in the systems of different collectors and depressants, and the influence of different flowsheets on the copper-molybdenum separation have been investigated by actual ore flotation tests, The separation problem of copper-molybdenum for a carbon-containing copper molybdenum ore has been solved.INTRODUCTION In this paper, technological mineralogy, small experiment of flotation recovery of copper Molybdenum ore, and expansion experiment of mineral recovery of copper Molybdenum ore are introduced. (1) The results of process mineralogyshow that the content of copper is 0.42%, molybdenum is 0.021% in the raw ore, they mainly exist in the form of sulfide, with low oxidation rate. (2) The results of flotation tests show that the combination of butyl xanthate and isopropyl ethylthionocarbamate reagents is effective collector of copper-molybdenum mixed flotation for carbon copper molybdenum, (3) When the grinding fineness is -0.074 mm taking 71%, and regrinding fineness is -0.038 mm taking 85%, the flowsheet of first copper-molybdenum mixed flotation and then regrinding rough concentrate and last separation flotation of copper and molybdenum was adopted, which realized the effective separation of copper and molybdenum for carbon-containing copper molybdenum ore. Good flotation indexes were gained with copper concentrate containing 20.96% copper and copper recovery 90.06%, and molybdenum concentrate containing 46.78% molybdenum with molybdenum recovery 72.68%. (4) The seven days average concentration index of scale-up the continuous dressing experiment is as follows, the copper content in copper concentrate is 20.16% and the recovery is 89.61%; the molybdenum content in molybdenum concentrate is 24.58% and the recovery rate is 74.09%."

Jan 1, 2018

By Felix M. Zhuravlev, Vitalij P. Lyalyuk

"While there is a large industry based on recovering platinum group metals (PGM) from complex sulphide ores containing Cu and Ni, there is little information on the thermodynamics of the matte phase formed on smelting the ore and in particular the behaviour of Pt in the matte.The equilibrium between metallic platinum and industrial mattes was studied in a series of experiments where a small quantity of matte (5g) and platinum foil of 150 µm thickness (0.5 g) were equilibrated in magnesia crucibles at 1400°C under conditions where the oxygen and sulphur partial pressures were controlled.The chemistries of the phases were determined from EDS analysis using a scanning electron microscope. Line scans were initially used to confirm that the foils had attained a uniform composition across their thickness. The composition of the matte was determined from analysis of an area of matte including the small metallic droplets and dendrites.The distribution of Pt in Cu-Fe-Ni mattes (Pt: 1.5 – 3%) and solid Pt alloys (Pt: 54 – 72%) was studied. For a matte of base composition 45%Fe, 11%Ni, 8% Cu, at a base temperature 1400°C, the following behaviour was observed for the Pt distribution ratio:Under the range of sulphur and oxygen pressure of this study (log pO2 from -15 to –12.2, log pS2 from – 4.6 to –2.2), the distribution ratio of Pt between matte and alloy was independent of the sulphur and oxygen pressure, having a value of 0.04.The Pt distribution ratio increased from 0.02 to 0.08 with temperature from 1340 to 1450 oC.For mattes where the proportions of Cu and Ni were kept constant, a slight decreasing trend was shown for the distribution ratio of Pt versus the iron content (37 to 53%) in the matte but was not confirmed because of experimental uncertainty."

Jan 1, 2003

By Steven Wright, Sharif Jahanshahi, Shouyi Sun

"While there is a large industry based on recovering platinum group metals (PGM) from complex sulphide ores containing Cu and Ni, there is little information on the thermodynamics of the matte phase formed on smelting the ore and in particular the behaviour of Pt in the matte.The equilibrium between metallic platinum and industrial mattes was studied in a series of experiments where a small quantity of matte (5g) and platinum foil of 150 µm thickness (0.5 g) were equilibrated in magnesia crucibles at 1400°C under conditions where the oxygen and sulphur partial pressures were controlled.The chemistries of the phases were determined from EDS analysis using a scanning electron microscope. Line scans were initially used to confirm that the foils had attained a uniform composition across their thickness. The composition of the matte was determined from analysis of an area of matte including the small metallic droplets and dendrites.The distribution of Pt in Cu-Fe-Ni mattes (Pt: 1.5 – 3%) and solid Pt alloys (Pt: 54 – 72%) was studied. For a matte of base composition 45%Fe, 11%Ni, 8% Cu, at a base temperature 1400°C, the following behaviour was observed for the Pt distribution ratio:Under the range of sulphur and oxygen pressure of this study (log pO2 from -15 to –12.2, log pS2 from – 4.6 to –2.2), the distribution ratio of Pt between matte and alloy was independent of the sulphur and oxygen pressure, having a value of 0.04.The Pt distribution ratio increased from 0.02 to 0.08 with temperature from 1340 to 1450 oC.For mattes where the proportions of Cu and Ni were kept constant, a slight decreasing trend was shown for the distribution ratio of Pt versus the iron content (37 to 53%) in the matte but was not confirmed because of experimental uncertainty."

Jan 1, 2003

By Vladimir S. Zharov, Vyacheslav A. Tsukerman

"Conceptual imitative dynamic model of developing enterprises for medium and long-term period permitting to ensure coordination of interests of the enterprise and territorial environmental authorities has been developed to enable the process of the prognostication and management of a concentrating mill development, in which a symbol language and terminology familiar to the manager of the company are applied. An algorithm of practical application of this model of company development was elaborated as well as a general methodological approach to the prognostication of the development and procedures of its implementation. The general methodological approach to the implementation of the model has been defined. Within the framework of system approach, a concentrating mill is considered as a subsystem of an ore mining and processing company or a mining and smelting one. A concentrating technology is considered in dynamics, its change is determined by the task of making the company operation profitable. Technological indicators are secondary relative to financial and economical indexes. At the same time, technological and economical indexes are determined in their interrelation with ecological parameters. The elaborated model allows us to estimate all necessary economic, financial and technological indexes in their interrelation both for the company as a whole and as separately redistributed estimating the basic prognostication documents - accounting balance-sheet, profit and loss report, as well as the funds flow statement. When varying the managing parameters, all necessary result-producing financial and economical indexes are estimated and a need in and a possibility of an external funding by various sources are considered.The implementation of the model enables one to determine the required scale of production capacity, as well as the amount of raw-material resources needed. In case of shortages of the latter, there should be considered various scenarios of the production capacity enhancement or the possibility of commissioning of new sites or deposits and introduction of improved technologies."

Jan 1, 2003

By D. Bastin, J. Frenay, J. Dassas

"The Luiswishi deposit belongs to the Cu-Co deposits of the Southern Group of the Katangian Copper Belt and is operated by a joint venture between EGMF (Entreprises Générales Malta Forrest) and Gecamines (Générale des Carrières et des Mines). The Cu-Co ore is beneficiated by the sulphidization process at the NCK (New Concentrator of Kipushi) at Kipushi.Sulphidization followed by flotation with sulphydryl collectors is a common practice for the treatment of oxidized base metals ores. This process is complex and its application at the industrial scale is quite sensitive. In Central Africa it is also a cost intensive treatment as the sulphidizing agent has to be imported. In order to improve the metallurgical performances and to optimise the economics of the process, a laboratory research program was carried out by the Laboratory of Metallurgy and Mineral Processing (MTM) of the University of Liège in close collaboration with EGMF and Gecamines. This program included the study of various flotation reagents as dispersing, depressing and activating agents.This paper presents the results obtained with the use of ammonium sulphate as activator of the sulphidized xanthate flotation. Although ammonium sulphate has been mentioned in the literature as a promoting agent of the sulphidized xanthate flotation of malachite, its effects on the flotation of cobalt oxides was not known.The testworks were carried out on various oxidized siliceous ore types from the Luiswishi deposit. A 1.7 l Agitair laboratory flotation cell was used. NaHS and potassium amylxanthate were respectively choosen as sulphidizer and collector. A mixture of gasoil and tall oil (90/10) was used as secondary collector. A multistage sulphidization was realised. Values of pH were followed during the different tests and an ion selective electrode Ag/Ag2S was used to control the Es potentiel evolution during the stepwise addition of the sulphidizer."

Jan 1, 2003

By Marianella Perez, Williams Calderón, Gonzalo Montes-Atenas

The lack of fresh water sources, particularly in the Northern part of Chile, has driven the mine sites to search for new and sustainable paths to obtain water resources to run minerals processing operations. Among them, the use of seawater in concentrators appears as an interesting solution to this problem. However, the presence of seawater will have an impact onto the operation, not only because it will enhance corrosion reactions in the equipment installed in a plant, but also because it may affect how particles will effectively be processed across the numerous unit operations existing in the mine site. Among such unit operations, the grinding stage is a highly regarded as it defines the success of the separation of valuable minerals from gangue material in the froth flotation operation. Then, one important aspect to be addressed is to understand how the presence of seawater will affect the different mechanisms acting during the operation of a ball mill. The aim of this research work is to assess the effect of changing the aqueous matrix from process water to seawater in ball mills onto the mill performance. The methodology considered the use of Fluent® software and its capabilities to run numerical simulations with heterogeneous media. On one hand, from the data analysis, it is possible to infer that breakability mechanisms should not be significantly affected. On the other hand, the high ionic strength of the matrix should impact importantly particle transport mechanisms within the mill. Particularly, when transporting finer particles. Rheology results were in agreement with previous published research studies suggesting the suspensions to behave as Newtonian, Dilatant o Pseudo-plastic fluid depending on the amount of fine particles present in the grinding media. The latter will result in changes in the residence time of particles in the mill producing overgrinding or an excess in the circulating loads.

Jan 1, 2014