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By U. Ulusoy

Surface roughness and acuteness are known as the two of the main properties of the particle morphology affecting the behavior of the powders in the process. Since the techniques used for the morphological characterization of powders by 2-dimensional microscopic measurement from the polished sections that have some disadvantages, the 3-dimensional analysis has often relied on measurements of particle morphology. A review of literature data was presented for high-grade barite and pyrite particles ground by ball and autogenous mills to determine the morphological properties using a new 3-D approach based on BET nitrogen gas adsorption and Permaran methods. Micromeritics Flowsorb II 2300 instrument which employs BET nitrogen adsorption technique was used for the specific surface area measurements and the roughness of the particles. Permaran (manufactured by Outokumpu Oy) was used for the measurements of airflow resistance of powder samples for the acuteness. Spherical glass beads were used as reference sample for the acuteness measurements. The obtained parameters, which are surface roughness and acuteness, were corre-lated with the floatability performance of those mineral particles. The flotation performances of those particles ground in different mills (ball and autogenous) were also evaluated by a Hallimond tube. The results showed that lower roughness and acuteness values caused higher flotation recoveries for both barite and pyrite particles that were tested independently in different type of the mills. In other words; particles with smooth surfaces resulted in better floatability for barite and pyrite minerals studied.

Jan 1, 2014

By Shuji Owada, Yang Geng, Natsuko Kuroki

Micro-bubble flotation is considered to be an ideal method for the separation of fine or ultra-fine particles, which are difficult to be separated with conventional flotation and other solid separation technologies. Micro-bubble flotation can increase the probability of bubble-particle collision more than conventional milli-bubble flotation. However, there are also some problems. For example, it is known that the rising velocity of micro-bubble is quite low; therefore, the flotation rate reduces. And also, the bubble-particle adhesion probability becomes lower than that of milli-bubble flotation, which is proved in our prior research. In this paper, we applied ultrasonic irradiation to the micro-bubble flotation system in order to solve the above problems and focused on the bubble-bubble and bubble-particle interactions. For clarifying the behavior of bubble-bubble interaction, bubbles behavior was recorded by high-speed camera under irradiation of various ultrasonic frequencies. As a result, in the case of bubble-bubble interaction, it is proved that bubbles are highly coalesced by ultrasonic irradiation especially in the lower frequency and it can enhance more precise separation. In the case of bubble-particle behavior, it is found that the floatability become higher with the ultrasonic irradiation of higher frequency, and it is indicated that ultrasonic irradiation might improve the bubble-particle adhesion probability. Additionally, it is also found that the apparent CMC of the micro-bubble flotation under the ultrasonic field become much lower with higher frequency than with lower frequency, and it is suggested that the dramatic improvement of hydrophobization is achieved.

Jan 1, 2014

By Teemu Väyrynen, Matti Vilkko, Antti Jaatinen, Pekka Itävuo

"This paper shows that smooth and accurate feed-hopper level control is essential for consistent cone crusher operation. The objective of the paper is to define the best practices for tight control of cone crusher feed-hopper level. The paper discusses the challenges involved in a delay-dominant level control problem (specifically, dead-time-induced performance and stability issues, mass flow disturbances, process and actuator non-linearity) and proposes five corresponding control structures. The performance of the proposed control structure candidates is evaluated in a simulation study and, finally, a full-scale experiment is conducted for the best-performing candidate. The results of this study emphasize the importance of control structure selection. While the most obvious control structures failed to deliver the desired performance, the best result was achieved by using control structures that eliminate the conveyor transport delay (dead-time) from the control loop. In practice, the control loop dead-time can be eliminated by either using an actuator (variable-speed feed conveyor) that is connected directly to the feed-hopper, or by redefining the process boundaries closer to the used actuator (regulate the circuit mass balance instead of feed-hopper level). The presented control structures provide means to achieve a consistent cone crusher performance and size reduction. This facilitates efforts to improve the plant’s performance and increases the plant’s overall stability."

Jan 1, 2014

By V. A. Chanturiya

In Pt- and Au-keeping complex ores processing, about 10% ~ 15% of noble metals are lost with true tailings that are due to low floatability of Pt- and Au-keeping minerals by the conventional collectors. With the aim to achieve the effective recovery of noble metals at flotation of Pt-Cu-Ni and Au-keeping ores organic complex reagents keeping electron-donating atoms of nitrogen, oxygen, sulfur or phosphorus may be offered as selective collectors for the indicated minerals. These rea-gents tend to form complex compounds with PGM. Besides this, Cu-Ni-Pt and complex Pt and Au carbonated mica ores are characterized by finely disseminated (up to nanometer size) mineral forms of Pt in multivalent states. In this connection, the use of a combination of the strong ionic collectors with nonionic reactants that are capable to derivate complex compounds with multivalent PGM seems to be expedient for this type of ores. In the research new complex reactants were tested such as cyclic alkylene-trithiocarbonates, oxyalkyl butylxanthogen acid ethers, a combination of the collectors ? mercaptobenzothiazole (MBT) and dialkyldithiophosphates (DTP). Sorption and flotation tests were made with monomine-ralic samples of chalcopyrite, pentlandite, pyrrhotite, pyrite, and Pt-Cu-Ni sulfide ore samples. Sorption properties were examined by the extractive UV spectrophotometric method and potentiometric measurements. To indicate a structure of modified xanthate solutions the method of a thin-layer chromatography (TLC) was applied. The chromatographic behavior of the basic components of modified xanthate solution ? ButX, cyclic propylene-trithiocarbonate (PTTC), diethyl-dithiocarbamate (DEDC) and the product of its modification ? oxypropyl-S-ether of dithiocarbamatic acid was studied on plates ?Silufol UV ? 254?. The composition of organic solvents and its ratio in a mobile phase was deter-mined for simultaneous chromatography of the main components of a reaction mixture. It was found that operating selectivity of MBT, DTP and cyclic alkylene-trithiocarbonates incorporated in modified xanthate in relation to Pt-Cu-Ni and Au-containing sulfide minerals might be explained by an electoral sorption of this nonionic collector on a surface of the minerals studied. It was demonstrated that the application new reagent modes with the use of a combination of designed complex reactants helped to increase the extraction index of Pt- and Au-keeping minerals from complicated ores.

Jan 1, 2014

By R. Venugopal

Hydrocyclones have been used extensively for more than 100 years to classify mineral slurries for recirculation in grinding circuits. Sometimes hydrocyclone classification is carried out in more than one stage to improve the efficiency of classification. Factors affecting separation efficiency include fluid velocity, density, and viscosity as well as the mass, size, and density of the particles. The geometric configuration also affects its efficiency; it includes parameters like cyclone diameter, underflow and overflow diameter, position of vortex finder, height of the cyclone, feed inlet geometry, and diameter etc. Besides changes in the basic parameters some modifications in cyclone has also been introduced from time to time which have affected its efficiency, some of these are :-(i).Introduction of magnetic force along with the centrifugal and drag force to control the flow of the magnetic particles inside the chamber.(ii). Introduction of sparger, air is introduced in the chamber in the form of bubbles, to control the flow of fine particles and hydrophobic particles. (iii). Introduction of dilution technologies for the dilution of thickened underflow. (iv).Introduction of new model. In spite of wide use and simple geometry, the real working principle of hydrocyclone chamber is extremely complex because of the swirling turbulent flow inside the device. In order to get more knowledge about hydrocyclones and to increase its efficiency, past 10-15 years simulation techniques are being developed. The simulation models also enabled a deeper insight into the static and dynamic behavior of hydrocyclones. Therefore, more emphasis on simulations by methods like Computational Fluid Dynamics (CFD), Finite Element method (FEM) is given. Overall, a status review of the work carried out on the analysis of hydrocyclone performance, modeling approaches and its contribution in the efficiency of mineral processing operation is highlighted.

Sep 1, 2012

By S. J. Ma

To look into the ionic release laws of the sulphide tailings in some copper mine, the effects of the soaking period, temperature, oscillating speed, and pH of the solution on the heavy metals ionic re-lease were investigated through static soaking leaching experiments. The results show that Cu2+, Zn2+, Pb2+, Cr3+ are of different leaching behaviors with soaking period. The ionic concentration in soaking solution for four ions has a great gap. Zn2+ is more easily released out of sulfide tailings than Cu2+, Pb2+, Cr3+ , and the ion release concentrations are not proportion to their contents in the tailings. The time for each ion to reach its maximum concentration are different. The minimum concentration do not occur at the first day. Each ion concentration shows different fluctuation characteristic during soaking process. Solution pH, oscillating speed, and temperature affect the releases of Cu2+, Zn2+, Pb2+, Cr3+ out of the tailings to different extent. The effect of pH value on ion re-lease for the four ions ranks as Zn2+>Cu2+>Pb2+>Cr3+, the oscillating speed ranks as Pb2+>Zn2+>Cu2+>Cr3+, and the temperature ranks as Cr3+>Pb2+>Zn2+>Cu2+.

Jan 1, 2014

At times the phosphate industry, in Florida, encounters phosphate rock that gives lower than expected P2O5 recovery in the rougher plant section. The drop in recovery is typically 10% and as much as 30% or more. Variations in feed quality from day to day, shift to shift and even from drag-line to drag line, represent a challenge to the beneficiation plant operators and reagents? suppliers. Therefore, this characterization study has been initiated to identify the reasons for the differences in flotation behavior of such feeds. The study involves many samples to cover such variations. The characterization work includes: ? Mineralogical and chemical analysis; ? Size, shape, surface roughness and porosity analysis; ? Surface charge and surface contamination with other phases (minerals); ? Clay content and its relationship to phosphate and silica particles. The results correlated with flotation data and adsorption density measurements clearly establish the statistically significant variability in characteristic features that influence flotation response. This article discusses results from the above listed studies. On the basis of the obtained data, recommendations of practical approaches to overcome the problem of feed variability in phosphate flotation plants are delineated.

Jan 1, 2014

By M. P. Krasteva

The froth flotation process for separation of mineral ores depends on the establishment of care-fully controlled froth. The formation of very stable froth in the flotation circuit is a problem that may occur in many plants, resulting in down-time, low quality and grade of final product and considerable expenses. Froths build up on the top surfaces of thickeners, tanks and flotation cells until they overflow, or until the efficiency of the circuit is impaired. A similar problem exists in Assarel concentrator, Assarel-Medet PLC, Bulgaria. Copper and copper-pyrite ores are dressed in Assarel concentrator. They are characterized with variable and complex mineral and physical composition. During the flotation cycle, resilient and difficult to break-down froth is formed, which subsequently impedes the process of thickening and clear overflow obtaining. Due to this problem continuous sampling in the cycle of thickening was conducted. The mineralogical, chemical composition, particle size distribution and solid phase content of the products were determined. It was established that the solid phase of the froth build up on the top surface of the thickener differs considerably from this one of the thickener underflow. The data clearly indicates that a separation process takes place on the top surface of the thickener ? fine particles of chalcopyrite are concentrated in the froth. The role of chemical reagent addition in the break-down of the flotation froth is investigated in terms of surface chemical phenomena involved in the stabilized froths. Measurements of the coper minerals wettability and surface tension at the air/liquid interface were performed. The surface active agent AERODRI® dewatering aids were laboratory tested. Bench-scale froth collapse tests were conducted. Reagent addition into pulp-froth system promotes and leads to a bubble coalescence, an improvement of the wetting of the mineral particles and a decrease of the surface tension at the air/liquid interface. The results of the laboratory experiments showed that the presence of the surface active agent leads to considerably decrease of the froth stability and the destruction of the deleterious froths build up on the top surface of the thickeners in Assarel concentrator.

Jan 1, 2014

By S. N. Shahcheraghi

Grinding is one of the most important and expensive steps in mineral processing allocating about 70% of the total energy in the plants. Nowadays, for optimizing the energy consumption in these equipments, the rock behavior and its size distribution during the crushing have been normally predicted using selection and breakage functions to be able to optimally model and design grinding circuits. For this purpose, the case of Miduk copper mine in Kerman province, Iran was studied. The samples were taken from primary ball mills feed and were subject to screen analysis to achieve uniform sizes. Then, selection and breakage functions were determined at the different grinding times in laboratorial ball mill. Finally, ore size distribution in different grinding times was estimated using MATLAB software

Sep 1, 2012

By M. Rehor

The importance of brown coal as a raw material is currently given by growing energy needs of Czech Republic. More than 70% of mined brown coal comes from North Bohemian Basin these days. Mining of brown coal is run in four mining locations. They are geologically different and the parameters of mining coal are quite different too. This requires a little bit different methodology of both extraction and reclamation. Methods of reclamation works in the region are given mainly by the characteristics of overburden rocks appearing in the upper horizon of recuperated localities. The difficulties of the North Bohemian mine dumps reclamation works are caused by extremely unfavourable properties of rocks poured down to the majority of mine dumps. These are mainly rocks of the overlaying strata and the rocks strata of brown coal bed. Main materials poured down to the mine dumps are sands, clayey sands and kaolin ? illitic clays. Admixtures in filled rocks consist of organic (coal) mass, siderite and pyrite. These rocks are mechanically instable with respect to the wind and water erosion and during weathering they are getting unfavourable, acid (phytotoxic) nature, due to the influence of SO3 and Al ions. External and internal dumps of open pit mines are significant part of the North ? Bohemian landscape sustained by excavation. Their as fast as possible preparation and gradual integration into ecosystem of the area is interest of both citizens of region and mining companies. The paper briefly summarizes the methodology of restoration of the largest dumps of the North Bohemian Brown Coal Basin and the results of analyses and evaluation of samples taken on restored localities Rado-vesice dump, Strimice dump, Ru?odol dum pand internal dump of Bilina mine. An example of modern non-tradicional restoration methods is the restoration of internal dump of Bilina mine (application of power plant stabilizer). According to observations and results of sample analyses the methods of restoration were selected to limit the erosion influence, adjust the chemical and physical composition of surface of Radovesice and Strimice dumps. The application of marlites and bentonite prevent the unfavourable weathering processes on dump surface. Compensation of Quaternary sediments was artifically formed here. The need of marlite ploughing in, application of organical substrates and vegetation preparation was proved on Radovesice dump. The conception of landscape reclamation of the largest dumps after finishing of mining, methodology of technical reclamation and well considered using of fertilizable soils are main results presented in this article.

Jan 1, 2014

By H. R. Manouchehri

Large variations in flotation characteristics of minerals have been observed in winter and summer in plant practices as a result of changes in pulp temperature. Variations in temperature may affect the quality for pulp and related process water through changes in dissociation of different chemical species within the pulp, as well as changing in gas and metal hydroxide solubility, reagent adsorption and its stability on mineral surfaces, water/pulp viscosity, etc. All of these affect the flotation characteristics of specific mineral to some degree or another. It has been observed in Cu-Pb-Zn and/or Pb-Zn sulfides flotation that sphalerite (ZnS) flotation is strongly affected by changes in pulp temperature. Plant practices have shown that at the both low, e.g., T <10-12°C, and high, e.g., T > 60°C, the recovery for copper activated sphalerite is dramatically dropped. Within this paper the effect of pulp temperature on flotation characteristics of sphalerite is brought into considerations and laboratory flotation tests were conducted in conjunction with surface and solution chemistry analysis to understand the effect of temperature on sphalerite recovery. The effect of temperature seems to be complex since the temperature affects both the physical (hydrodynamics) and chemical phenomena in the flotation cell. In fact all sub-processes in flotation, i.e., collision, attachment and detachment, are affected by changing in temperature. Experimental results indicating that at alkaline pH values, e.g., 8.5 to 10.5, the recovery for copper-activated sphalerite is dramatically reduced when temperature is below 10-12°C, which is in agreement with plant practice at Boliden?s Garpenberg plant in Sweden. However, results from other studies indicated that the zinc recovery is also considerably decreased at high pulp temperatures, i.e., 62°C and above.

Sep 1, 2012

By J. J. Liu

In the Bayer process, control of alumina trihydrate particle size, oxalate stability and morphology and foaming is crucial for improving the yield and quality of alumina trihydrate. One way to economically achieve such control is to employ specifically developed chemical additives, termed, crystal growth modifiers (CGM?s). In this paper, the mechanism of action and practical application of CGM?s in the Bayer process are summarized. The application of CGM additives allows for both enhanced agglomeration and secondary nucleation control, and hence coarsening of the particles. Current research efforts have utilized the information gained from mechanistic studies to enhance the performance of CGM products. It was demonstrated in both laboratory tests and industrial operations that the newly developed CGM formulations have a range of properties with enhanced performance, compared to the current commercial products.

Jan 1, 2014

By B. McFadzean, S. Geldenhuys

"Dynamic froth stability tests have found widespread application to quantify froth performance. However, little to no attention has been given to scale parameters in the performance of these measurements. One of the most frequently changing scale parameters in the laboratory scale is the column diameter as this directly influences the amount of material needed for testing. Four different column diameters (50, 100, 200 and 300 mm) were used for this study. Column diameter experiments were done on an industrial scale by means of manual tracking of froth growth versus time. An increase in measured dynamic stability was seen with increasing froth column diameter, which reached a limiting value at large column sizes. It is thought that this behaviour is controlled by the differences in drainage rates of the bulk froth compared to froth in contact with the wall. The column diameter required to represent full-scale froth stability is proposed. A ratio of column surface area to total bubble surface area was used to correct for different column diameters.INTRODUCTIONThe froth phase in flotation contributes significantly to the overall performance of the process (Zanin, et al., 2009). Numerous parameters have been investigated to quantify froth performance, most notably froth recovery (Feteris, et al., 1987; Seaman, et al., 2004; Vera, et al., 1999). Experimentally gathering data to determine froth recovery is challenging and for this reason froth stability has been highlighted as a possible alternative.Froth/foam stability is defined as the time of persistence of the froth/foam and is affected by numerous factors, such as: drainage of the liquid in the lamellae (gravitational and capillary), viscosity at the bubble surface, thickness of the electrical double layer and gas diffusion through liquid films caused by pressure differences between bubbles (Aktas, et al., 2008; Beneventi, et al., 2001). It is well documented in both froth and foam literature that froth/foam stability will heavily influence the performance and appearance of the froth/foam phase (Ata, 2012; Farrokhpay, 2011; Weaire, et al., 2005). Experimentally this has been explicitly proven as an increase in froth stability, characterised by water recovery, usually results in an increase in both valuable mineral and solids recovery (Wiese, et al., 2011; Banford, et al., 1998)."

Jan 1, 2018

By S. Koca

Vast amount of fly ash, bottom ash and slags, are produced each year due to coal combustion in thermal power plants. These products consist of mainly unburned carbon and inorganic compound (such as: silica, alumina, iron oxides, magnesium oxide, phosphorus oxide etc.). These are valuable minerals and can be recycled or recovered if properly processed. One third of the material find application as an ingredient in cement and other construction products, the rest is held in dams or similar dumps, which results in a hazardous impact on the environment, polluting soil and ground water. The unproductive use of land, the associated long term financial burden maintenance and negative environmental impacts have led to realization that alternative uses for combustion by-products as a value added product beyond incorporation in construction materials are needed. At present, there is an intensive search to increase their uses. Other uses of coal combustion residues include as raw material in brick and ceramic tile fabrication, as filler in plastics and paints, extraction of valuable mineral materials, production of zeolites and soil and mine waste treatments. Separation of unburned carbon from bottom ashes by means of flotation was conducted in order to increase the possibility of the recycling of coal combustion wastes. In the flotation experiments collector, dispersant and frother amount, pulp density and pH were tested as variables. After first stage flotation experiments, at optimum conditions, the carbon content was reduced down to 5.58 % in the tailings fraction. This fraction meets the industrial specifications and can be utilized as a cement additive. At the same conditions the carbon content of the concentrate increased to 44.72 % at a carbon recovery of 65.81 %. After the cleaner stage flotation experiment the carbon content of the product is enhanced to 62.53 %. This fraction can be blended back into the coal feed to the power plant boilers.

Jan 1, 2014

By J. Gong

Fine mineral particles pose two challenging problems in froth flotation, i.e., ineffective recovery of fine hydrophobic particles and mechanical entrainment of fine hydrophilic particles. The first problem has attracted much research effort while the second problem has received much less attention. We have recently proposed a method to deal with mechanical entrainment, i.e., utilizing the flocculating power of polymeric depressants to flocculate fine gangue particles and making the flocs big enough so that the mechanical entrainment of these particles can be reduced or eliminated. In this paper, we report results on the use of polyethylene oxide (PEO) in controlling quartz gangue in the flotation of sulphide ores. PEO was found to flocculate fine quartz and lower its entrainment. It was also found to modify air/water interfacial properties and acted as a frother, which could increase gangue entrainment. Nevertheless, when used at starvation dosages, PEO was found to significantly improve the grades of the floated sulphide concentrates.

Jan 1, 2014

By M. E. Ramírez

In this research bioleaching or extraction of iron present in a kaolin from La Virgen mine, Anti-oquia/Colombia, was carried out. Organic acids produced in SF with Aspergillus niger were used in the process. The fermentation process was carried out in 3 L aerobic stirred bioreactors, at a temperature of 30 °C, a stirrerd speed of 700 rpm, an initial pH of 4 and a fermentation time variable between one to 8 days, obtaining broth fermentation samples daily per bioreactor. For iron extraction, fermented broth from second to sixth day of fermentation was evaluated and it was found that the fermentation broth of the third day showed a larger potential for iron removal, 786 ppm, by using kaolin with an initial iron content of 1401 ppm. A set of tests using commercial organics acids such as citric acid and oxalic were carried out because those were found in the fermentation broth and it was found that oxalic acid presented three times more iron removal than citric acid.

Jan 1, 2014

By T. Kalliomäki, B. P. Wilson, M. Lundström, J. Aromaa

"The diffusion rate of cupric ions and limiting current density are important factors that determine the rate of copper mass transport in electrolytes proximal to the electrodes used in electrorefining. As a result, diffusion can critically affect both the rate and morphology of cathodic copper deposition thus it is crucial that it be optimized to improve production. The diffusion coefficient of cupric ion (DCu(II)) in copper electrolytes has been previously researched but the values detailed in the literature show significant variations and moreover arsenic - a common impurity - is generally excluded. Furthermore, in previous studies the models have only been validated with model solutions rather than real industrial electrolytes. In this study, the limiting current density and diffusion coefficient of cupric ion were defined for synthetic electrolytes containing copper (40–60 g/dm3), nickel (0–20 g/dm3), sulfuric acid (130–220 g/dm3) and arsenic (0–45 g/dm3). The cathodic limiting current densities were measured at three temperatures (50, 60, 70 °C) with linear sweep voltammetry using the rotating disc electrode (RDE) as the cathode. By utilizing the limiting current density, models for the DCu(II) were constructed using Levich equation. The validity of the DCu(II) model for technical use was confirmed through their application to industrial electrorefining electrolytes with known element concentrations. Consequently, this study provides improved models for limiting current density and diffusion coefficient of cupric ion that can be utilized for industrial process optimization.INTRODUCTION For an efficient copper electrolysis process, the mass transport of copper ions has to be effective. The main mass transport types of copper ions in copper electrorefining are diffusion and convection while the effect of migration is negligible. In order to maintain good mass transport, it is beneficial to keep both diffusion and convection high to maximize the limiting current density (jlim) (Bard and Faulkner, 2001). jlim is the highest current density that can flow in the cell, thus by maximizing jlim the deposition time can be minimized and the good quality of cathodic copper can be ensured. Thus, it is important to research possibilities that increase and optimize diffusion since slow diffusion in the electrolyte limits the rate of the process (Levich, 1947; Moats et al., 2000; Subbaiah and Das, 1989)."

Jan 1, 2018

By Carsten Gerold

The paper is giving an overview about successful operating Loesche Vertical ? Roller ? Mills (VRM) installations and summarises the main benefits of the dry compressive Loesche grinding technologies in Airflow- and Overflow-Mode. Some of these benefits are optimised energy efficiency of the grinding - classifying - circuits, increased mineral recoveries and decreased OPEX costs, at a parallel simplification of the process route. Within this paper the process values of the Loesche VRM are compared to existing or planned conventional grinding ? classifying circuits. Further advantages discovered in pilot trials and examples for new more efficient process route alternatives are given. The paper reports about production and pilot trial experiences obtained by crushing and grinding Iron Ore, Iron Ore Concentrates, Copper Shale, Copper Matte, Copper Slag, Titanium Slag, Tin Slag, Steel and Stainless Steel Slag with Loesche VRM.

Sep 1, 2012

By Duong Huu Hoang, Nathalie Kupka, Urs A. Peuker, Martin Rudolph

"The froth ability, froth stability and the froth structure are strong influences in flotation process i.e. on water recovery, bubble size, entrainment of gangue particle, flotation rate constants, grade and recovery. The labscale flotation of rich apatite ore with a high mass pull leads to significant changes in pulp and froth properties over time. The froth stability decreases with increasing the flotation time. These changes can be related to different solid contents, reagent concentration, froth heights and bubble size distributions. This study presents the results from froth studies and discussions on the particle size of fully liberated silicates and degree of entrainment based on automated mineralogy size-by-size analysis. The change of entrainment in a rich apatite ore batch flotation with time will describe more precisely by measuring froth properties using a Dynamic Foam Analyzer. It is concluded that the degree of entrainment is not only dependent on particle size but also the pulp density due to its effect on particle settling and also froth properties in varying resistance to particle drainage. Furthermore, entrainment models are applied to predict the effect of size, flotation time on entrainmentINTRODUCTIONFroth flotation belongs to the group of heterocoagulation separation techniques. Froth flotation is classically divided into two active zones, the pulp zone (where particle collection occurs) and the froth zone. A schematics drawing of the interaction between both zones is plotted in Figure 18 (Yianatos and Contreras, 2010). In froth flotation, the collision probability in the collection zone is governed by the physics of the process or hydrodynamics (Wills and Finch, 2016). The true flotation event in the pulp occurs when the hydrophobic valuable mineral particles collide with bubbles and formation of a stable particle-bubble aggregates moving upwards against gravity to the froth phase (Yianatos et al., 2009)."

Jan 1, 2018

By S. J. Liu

The conventional collector for bauxite mineral is oleic acid, which is highly insoluble and must be used in high dosage in bauxite flotation operations, that is the great drawback of oleic acid in use. A series of hydroxamic acid were synthesized, and their collecting ability to certain minerals in bauxite: diaspore, kaolinite were studied. The collecting power of various reagents to diaspore in an incremental sequence were shown as follows: benzyl hydroxamic acid<amylic hydroxamic ac-id<heptylic hydroxamic acid<oleic acid<octylic hydroxamic acid; while the incremental sequence of the collecting power to kaolinite was like this: benzyl hydroxamic acid<amylic hydroxamic ac-id<heptylic hydroxamic acid<octylic hydroxamic acid<oleic acid. It could be seen that octylic hydroxamic acid had the capability of high collectivity and good selectivity, and octylic hydroxamic acid was chosen to use in the following experiments. Reduced zeta potential showed the adsorption of the anionic collector on the mineral. By the adsorptive capability and IR tests, the adsorption of octylic hydroxamic acid on diaspore was determined to be chemical absorption, which was greater than that of oleic acid, as it was physical absorption. Results of floatation experiments on manually mixed minerals indicated that the collectivity and selectivity of octylic hydroxamic acid were better than oleic acid.

Jan 1, 2014