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By N. Tsoni

The separation and recovery of fine and ultra-fine particles during the processing of mineral commodities by conventional separation methods is difficult and inefficient. This is due to the problems posed by the very small size of the mineral particles. The fine and ultra-fine mineral particles are either generated during size reduction processes or are necessitated by liberation size. This problem is expected to deteriorate, as deposits of even lower grade are processed. The inefficiency of the conventional separation methods with regards to the processing of very fine particles leads to the loss of considerable quantities of mineral commodities to the tailings. Novel methods and techniques as well combinations of known methods have been tested over the years. Among them, selective aggregation, along or in combination with flotation, has been given much attention. This study deals with the application of hydrophobic agglomeration as a separation method for very fine particles. The selected mineral system is magnesite/quartz, due to its sensitivity to physi-cochemical separation methods. The aim was the selective agglomeration of magnesite using sodium oleate. Tests on single minerals revealed that separation seems feasible and efficient. The parameters examined were: pH, quantity of sodium oleate, conditioning time, and, finally, settling time. Tests carried out on artificial mixtures of the two minerals, under various proportions, confirmed the results obtained from single mineral tests but they were slightly inferior. Finally, hydrophobic ag-glomeration tests were carried out on single and artificial mixtures of minerals using sodium oleate and petroleum as reagents. The results show that the addition of petroleum improves the results. In conclusion, hydrophobic agglomeration can be applied successfully even for fine particles of difficult-to-be-separated systems such as magnesite and quartz.

Jan 1, 2014

By Juan B. Yianatos

"After almost 100 years, since the first commercial application began in Australia, flotation has shown an extraordinary growth and nearly 2 billion tons of ore per year are presently treated by flotation processes. During this time flotation has promoted a wide scope of research activities ranging from fundamental chemistry and hydrodynamic studies to studies of industrial operations. In general, fundamental studies have been mainly related to ideal situations. In recent years, however, large efforts have been focusing on achieving a better insight into the actual sub-processes provided by the development of new and more sophisticated instrumentation. Since the massive incorporation of flotation columns, around 15 years ago, a renewed interest in flotation fundamental studies, process modelling and new cell designs have been observed worldwide. The key role of the froth has been recognized as an independent and sometimes rate limiting process step. Thus, separation of pulp and froth process stages seems the most appropriate in terms of process modelling, diagnostic, design and scale-up purposes.In relation to flotation equipment development, until the middle of the 1970?s, only the sub-aeration mechanical cells were dominant. Since the 1980?s, the use of pneumatic cells and forced air mechanical cells has emerged strongly. Also, in the last decade, flotation equipment has shown a dramatic increase in size, reaching values of 200m3 in unitary mechanical cells and more than 300m3 in columns. The general feeling, however, is that, despite the great advance observed in terms of process knowledge, the mechanisms and principles of industrial flotation cells design and scale-up are still not fully understood.Advances in process instrumentation and control now in use allow for more efficient operations, both in metallurgical performance and savings in operating costs.INTRODUCTIONFlotation is a widely used process within the minerals processing industry, as well as being used for water treatment and de-inking of recycled paper. Froth flotation started in Australia at the beginning of the 20th century and since then flotation technology has made significant advances. Flotation was firstly applied to sulfide ores. The largest tonnages treated by flotation are copper and copper/molybdenum ores, handling about 50% of the total ore processed. Also significant are phosphate, iron ore and coal treatments. At present, Chile is the foremost copper producer in the world with around 35% of the world?s production. Figure 1(a) shows the evolution of copper production in Chile over the last decade. The total amount of fine copper produced in year 2001 was 4.7 million tons, from which 3.2 million tons was processed by flotation while 1.5 million tons went through LIX-SX-EW processes, which also showed significant development during the same period (Anon, 2001). The total flotation treatment of copper ores in Chile is about 325 million tons per year (Anon, 2002), so the world treatment of copper ore by flotation can be estimated at about 1 billion tons per year. Consequently a total of nearly 2 billion tons of ore per year is presently processed worldwide by flotation (Fuerstenau, 2001). In order to handle the higher tonnage of low-grade ore, a worldwide trend towards the development and use of larger flotation machines began in the 1960?s. Figure 1(b) shows that the trend became extremely marked from the beginning of the 1990?s, which is consistent with the strong increase in copper production during the same period."

Jan 1, 2003

By T. Laxmi

This paper details the optimization of rougher Wet High Intensity Magnetic Separator (WHIMS) using response surface methodology. The optimization is in parametric form and takes account of the major operating variables in WHIMS operation such as current in ampere and grid gap, in inch. The objective is to recover ilmenite mineral from red sediment deposits of Srikakulam, India by optimizing the rougher WHIMS. We predict mineral recoveries as a function of current and grid gap. Combination of these predictions with assay data provides predictions of mineral grades and recoveries. The optimized response was validated against data derived from laboratory-scale rougher WHIMS test work, comprising (i) mineral grade, (ii) mineral recovery, and (iii) separation efficiency of the process. We observed close match between the experimental and the predicted data over most of the operational range. This paper describes how the optimization was carried out using the response surface methodology along with MATLAB. The response surface was used to closely investigate the separation of ilmenite mineral by varying ampere and grid gap. The results show that under optimum conditions, such as 3.5 amp current (0.53 Tesla) and 2 inch grid gap, the mineral grade could reach, as high as 87.9% in the concentrate with 74.3 % recovery and 74.4% yield. Keywords: red sediment, wet high intensity magnetic separator, optimization, ilmenite, placer heavy minerals

Sep 1, 2012

By Masakazu Niinae, Kenji Aoki

"Electrokinetic soil remediation by electroosmosis and ionic migration is restricted to soluble substances. At a higher pH, the soil particles sorb more heavy metals than at a lower pH and the precipitation of heavy metals are promoted. Both mechanisms make heavy metals immobile, rendering cleanup more difficult and electrokinetic extraction inefficient.In this study, the effectiveness of introducing a complexing agent to enhance the removal of cadmium from kaolinite in the region of neutral pH by ionic migration is examined. The complexing agent selected was ethylenediaminetetraacetic acid (EDTA). The investigation was carried out in a laboratory-scale column containing kaolinite contaminated with cadmium. As the results of the study, cadmium migrates toward the anode without accumulation of cadmium and is successfully removed at the anode reservoir."

Jan 1, 2003

By S. Gaydardzhiev

Laboratory batch tests having preliminary and orientation character aiming at improvement of the molybdenum flotation at Ellatzite copper processing plant in Bulgaria have been conducted. The following technological parameters have been screened to study their influence on the grade and recovery of copper and molybdenum during the rougher flotation stage: flotation pulp density, pH, addition of secondary collector and replacement of MIBC by pine oil as a frother. The results have shown that slightly better grade/recovery figures could be obtained for both copper and molybdenum at lower flotation pulp densities. The addition of kerosene has improved the recovery of molybdenum however, on the expense of that of copper. The effects from pH variation and the replacement of MIBC by pine oil as a frother have been almost negligible.

Sep 1, 2012

By A. V. Kanarskay?

The research is aimed at involving in the processing of poor platinummetal natural and technogenic raw materials. The purpose of the research is the creation of a multifactorial complex of innovations in the system of ore preparation and separation cycles, which ensure a high efficiency of flotation enrichment of hard-to-treat raw materials. In the usual practice of enrichment, minerals of the platinum group (PGM) of less than 10 microns in size are the source of inevitable process losses. For poor raw materials, it is precisely thin PGMs that are characteristic, their proportion sometimes being almost 100%, and their opening leads to the formation of a large amount of slime, which adversely affects the efficiency of flotation. To reduce the yield of slimes and increase the selectivity degree of the opening of the PGM in the ore preparation cycle, a dry grinding scheme and pneumoclassification of the milling material has been developed to obtain fractions of different fineness, density and morphology of the particles. From 2 to 5-fold reduction in the yield of slurries for various ores has been achieved. The separation cycle successfully tested are: flotation of fractions in separate cycles with a differentiated choice of the reagent regime; preliminary selective flocculation of slime fraction material; use of a new generation of bioreagents for flocculation and flotation. A new approach to subsoil research is protected by a patent. The dependence of the efficiency of biocollectors on the composition of biomineral extract from the processed raw materials, which forms the basis of new reagents, is established. The possibility of obtaining the degree of extraction of PGM, native gold and sulphides from finely ground pre-fractionated poor ores with the use of biocollectors of at least 85% is proved. With conventional reagents, the extraction of PGM is 12-23% lower, with the use of traditional ore-preparation apparatuses, the PGM recovery rate was halved. Methods for the long-term storage and preparation in industrial conditions of biocollector reagents that do not require the purification of waste waters from them have been developed. The developed multifactorial system of intensification of flotation enrichment can be introduced to recovery PGM from tailings of enrichment of titanomagnetite, chromite and copper-nickel ores.

Jan 1, 2018

By Manochehr Oliazadeh

"Water shortage becomes a major challenge in mining industry. The best example is Chile where the Chilean authorities declared a state of emergency in 2012. Depletion of high grade ore-bodies necessitates the use of low grade ores. If the demand for metals remains constant, more low-grade ores need to be mined to produce the same tonnages of metals. This increases the water demand in mining industry. Mining industry competes with other industries such as agriculture and manufacturing. Agriculture and manufacturing consume 1500 and 2300 billion m3 water respectively. The global use is 4500 billion m3 while the mining uses 80 billion m3 of water per annum.To tackle the water challenges in mining industry and also avoid competing with other users for fresh water, many efforts have been made, including using lower quality waters to reduce the fresh water consumption in ore processing. Saline water or hyper saline water from seas or the ground is accessible; however the cost of desalination is remarkable. Desalination plants and associated pipelines and pumps capital cost can easily exceed $ 500 million. Saline water will certainly increase the operating costs due to high wear rate of mechanical equipment but at current situation of mining industry spending all this money upfront does not look attractive. Desalination leaves salt on land at mine site which may create environmental issues.Dry processing can be a solution for water shortage in mineral processing. Wet processes dispose tailings on land with little or no agricultural productivity. It also may contaminate surface and ground water and generate dust. This paper reviews the water consumption by various mineral commodities, discuss briefly about recent of application of salt water in mineral processes and finally discuss about dry processes as alternative solution for water shortage in mining industry."

Jan 1, 2014

By Caitlin Rogers

The environmental and economic sustainability of froth flotation is dependent on effective management, which in turn improves the performance of a concentrator. In economic terms this means improved recovery of valuable minerals, in environmental terms this means effective management of acid generating tailings. Three indicators were selected to measure the performance of an integrated flotation system. The system consists of two stages of flotation; valuable mineral flotation followed by environmental desulfurisation by froth flotation. The suitable indicators were selected based on their fulfilment of four attributes. An attribute is a desired aspect of an indicator. The four attributes were: comprehensive, relevant, sensitive and quantitative. Two environmental indicators and one economic indicator were selected. They represent revenue generation from valuable minerals and environmental cost of management. The suitability of the selected indicators was shown using illustrative scenarios.

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 Markus A. Reuter, Yongxiang Yang, James R. Post

The packed coke bed in the lower part of an iron making blast furnace, the dead man, dissolves slowly in a pool of hot metal, which is tapped regularly. The coke particles of the dead man not only exhibit a size distribution, but also their size distribution is non-uniform throughout the dead man and as a result, the porosity of the dead man is non-uniform. This causes the flow of hot metal through the dead man to be irregular and non-uniform, bringing about channelling in the coke bed. Channelling is detrimental to the refractory lining life of the hearth of a blast furnace. Using population balance modelling and a porosity model it is possible to keep track of the local changes in size distribution and bed porosity during dissolution of coke particles. Numerical simulations show that carbon dissolution from a packed coke bed (with particles which exhibit a size distribution) increases the average porosity, decreases the mean particle size and changes the size distribution to a distribution with a smaller size range. Influence of the type of initial size distribution (mean, variance) is investigated. The calculated changes in porosity are used to dynamically adapt the flow and the mass transfer (kinetics) during calculations. This approach provides the possibility to implement dynamic porosity calculations for CFD applications, and thus simulate the results of various coke types and particle size distributions on dissolution and flow behaviour.

Jan 1, 2003

By Carlos Gualdron, Elizabeth Gomez, Rafael Bolivar

The productivity index of the Coopracarcegua Ltda., a mid-size coal mining company of Norte de Santander, Colombia, was related absenteeism using accident, productivity and profit data four years. The analysis was based on type, severity and frequency of accidents, number of absentee days; price per metric ton, and other relevant parameters. The enterprise is formed by 5 different mines of thermic coal, each one with different exploitation technologies and different productivity. Each mine was analysed separately and the loss of profit due to absenteeism was calculate for each one. The study showed that the foregone earnings due to absenteeism in terms of the whole productivity of the enterprise was about of 6.6% of the total profit average the 4 years, with calculated values of 14.7%, 3.5%, 8.4% and 4% per year in the evaluated period. The study identified that the most important cause of absenteeism was "General Disease". The foregone earnings in 2009, the highest loss for the analysed period, was about US$ 0.937 million and during the whole evaluated period was US$ 2.46 million.

Jan 1, 2014

By B. Z. Wu

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

Jan 1, 2014

By N. N. Ngoepe

Positron Emission particle tracking (PEPT), which makes use of a radioactively labeled tracer particle, a positron camera and a tracking algorithm has been shown to be a viable method for studying flow properties in both the pulp and froth phases of flotation cells. Detailed velocity measurements of 300-400 µm glass beads were extracted to assess turbulence from velocity fluctuations in a micro flotation cell. The effects of particle speed and orientation at the instant of attachment events were studied. A minimum speed of 0.16 m/s was needed for a collision to lead to attachment. The most attachment events happen when the particle is directly in line with the inlet tube at 90o.

Sep 1, 2012

By M. Abdollahy

In this paper, the hydrophobicity of chalcopyrite particles produced with different laboratory mills has been studied; different grinding mechanism in themills made some changes in particles shape, Image Analysis (IA) method was used to determine the shape properties of chalcopyrite particles which are ground by a laboratory ball mill, rod mill and ceramic ball mill. The shape characters are stated in terms of shape factors such as circularity, convexity, roundness and regularity factor. Hallimond tube was used to float chalcopyrite particles followed by determination of critical surface tension of particles, this parameter used as a criterion to study the wetting behavior of chalcopyrite particles. The correlation between shape properties and critical surface tension of chalcopyrite particles showed that the hydrophobicity of chalcopyrite was affected by the shape. Investigations showed that the circular, round and more convex particles that produced with ceramic ball mill had lower hydrophobicity with higher critical surface tension (?c). The results also showed that the hydrophobicity of particles ground by ball and rod mills increased with the decrease of roundness, circularity, convexity and regularity factor of particles. Keywords: chalcopyrite, particle morphology, flotation, image analysis system, micro flotation method, hydrophobicity, shape properties

Sep 1, 2012

By Gurubasayya Swamy

This paper presents the consequences of modernization and expansion of process plant by implementing SAG and Ball Mill and Carbon-in-pulp technology at the Hutti Gold Mine. From the inception of the process plant, it has undergone many changes for the improvement. In the beginning, only gravity recovery of gold was carried out by using Pebble Mills and Strake Tables. Later amalgamation, Cyanidation and Zinc precipitation and finally Carbon-in-pulp gold recovery system was implemented. Grinding plant was modernized by implementing SAG and Ball Mill and Knelson concentrator for free gold recovery as a result, the production rate, rate of recovery, reduced man power, Modernization and expansion of process plant has also yielded in safe and smooth running of the plant. Keywords: sag and ball mill, cip, modernization and expansion, productivity, gold recovery

Sep 1, 2012

By Roberto Galéry, Braz J. C. Filho, Marcelo M. Stopa, Douglas B. Mazzinghy, Priscila M. Esteves

"The purpose of the research is to monitor ball mill filling by means of signals usually measured in its electrical drive. The method is based on the mill torque estimated from rotor speed and induction motor stator voltage and currents. New signal processing is presented in both time and frequency domain for measurements in a dry laboratory ball mill. Statistical analysis is applied to time series resulting in good correlation to mill filling. Fast Fourier Transform (FFT) and power spectral density (PSD) also resulted in an accurate filling indicator. The proposed method does not need any sensor to be installed directly on the mill and requires only sensors usually available for motor control purposes. The experimental results showed that the method have potential to be used to construct an automatic system for monitoring operational variables in ball mills. The aim of this monitoring is to improve energy efficiency, reliability and productivity.INTRODUCTION Recently, a great number of papers have pointed the importance of ball mill filling monitoring and also of grinding control (Lu, et al., 2014) (Ramasamy, et al., 2005) (Tsamatsoulis, 2014) (Zhou, et al., 2009). Additionally, great amount of control techniques have also been presented with several complexity degrees (Tsamatsoulis, 2014). According to Eremenko (2015) the lack of effective and accurate methods for fill level measurement is the main reason that makes mill optimal control so complicated. It happens because nonlinearity, long time delay and time varying features of the ball mill turns difficult to develop a truly efficient method for monitoring filling. At the same time, fill level has a determining role in charge motion and consequently on particle breakage. For low levels of filling many energy is expended in impacts with very low breakage efficiency. Those impacts can also damage mill liner. In contrast, high levels of filling causes damping effects that reduces breakage and can also affect energy consumption. Based on this it is conclusive that fill level measurement of ball mills is an important issue for grinding efficiency. This fill level information can be used for operators to control ball mills and also for engineers to run simulations and improve confidence levels of circuit designs (Shi, 2016)."

Jan 1, 2018

Mineral processing is an energy and water intensive activity. Mill comminution equipment usually has high energy requirements which necessitate extensive cooling to remove heat. Cooling requirements are typically 10% to 20% of the comminution energy. If there is an adequate supply of suitable water, open water-based cooling systems are the simplest, cheapest and most energy efficient cooling method available. This paper describes a method to determine the water demand for open water-based cooling systems at a plant and to determine whether the mine has sufficient water to meet that demand.

Jan 1, 2014

By Y. F. Guo

Among the different valences of vanadium, V (?) is insoluble in acid, V (?) and V (?) is in-soluble in water but soluble in acid. Vanadium mainly exists as V (?) in vanadium titanium-rich material obtained by reduction -milling-separation from vanadiferous titanomagnetite. Therefore, the vanadium titanium-rich material can not be used to extract vanadium by acid directly. In this paper, the vanadium leaching was studied by oxidation roasting and acid leaching. Through oxidation roasting, vanadium is transformed from the insoluble V (?) into V (?) or V (?) in order to improve the leaching of vanadium. The results show that vanadium leaching increases significantly by oxidation roasting-acid leaching. Leaching of vanadium is up to 70.18% under the optimized conditions of roasting temperature of 950 ?, roasting time of 40 min, sulfuric acid concentration of 40%, leaching time of 4h, leaching temperature of 95 ? and liquid to solid ratio of 4 : 1.

Jan 1, 2014

By Z. H. Wang

The internal parameters of ball mill are very important in the grinding process and have significant impact on the grinding results. Accurate measurement of the internal parameters of ball mill is crucial and indispensable for optimization and control of grinding process. In this paper, a novel tri-sensor measurement method was used to measure the external signals (i.e., bearing pressure, sound intensity and power consumption) of ball mill. Mathematical models, which link the external signals of ball mill with its internal parameters, were established to predict the internal parameters of ball mill. Experimental results showed that the mathematical models could directly predict the internal parameters of ball mill once the external signals were obtained. The tri-sensor measurement method and the mathematical models proposed in this paper provided a new way and solid basis for optimization and control of ball milling.

Jan 1, 2014

By Z. H. Liu

We experimented with slurry which from one of coal preparation plant in Guizhou province and made researches on double hump gradation, one of critical factor of gradation technology, which can influence pulping character in the process of making coal water mixture (CWM). The purpose for it is to find the best particle gradation which can meet the requirements in concentration, viscosity, and stability for CWM. The final result is that the concentration, viscosity, stability of CWM can meet the requirement for industrial use while the rate of fine particle in the slurry is 70%~75% and the maximum concentration of 62%.

Jan 1, 2014