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By Luis G. Bergh

Today, large size mechanical flotation cells of 100 to 300 m3 are used in rougher operation in different flotation industrial plants, in Chile and worldwide. However, in spite of the advances in fundamental research and the notable growing in equipment size, with more complete instrumentation systems, there are still a lack of reliable data for industrial flotation modeling and simulation to advance in better control systems design. In this work, a model of a rougher flotation circuit, based on operating variables and parameters fitted from industrial data, obtained in some previous work, is used to develop a set of logic rules in order to aid operating decisions. The simulator was first used to sensitize the effect of changing the froth depth profile on target variables, and then to find out the best profile to reject common disturbances coming into the plant. The flotation circuit simulator was redesigned to incorporate an expert system following the proposed control algorithm. Several tests were performed to evaluate the control responses to different correlated series of input variables, such as feed grade, tonnage, particle size distribution, and solid percentage. Control alternatives are discussed based on the circuit simulator. Keywords: modeling, industrial data, flotation control, mineral processing.

Sep 1, 2012

By Ralph J. Holmes, Victor Sharp, Steven J. Spencer, Kevin J. Davey, Jonathan J. Campbell, Peter L. Phillips, David G. Barker

"Improved measurement tools for monitoring and control of AG/SAG mill performance have a high level of interest in industry. Historically, acoustic emission monitoring has been widely used on SAG/AG/ball mills and hydrocyclones to provide new information on the conditions inside these devices affecting their performance. The current work was focused on a new technique using surface vibration monitoring of a number of pilot-scale and production-scale AG/SAG mills to yield insights into the events occurring in the mills. The development of relationships between signal analysis outputs and mill operating conditions can be used for soft-sensor measurement of mill process variables. The technique used an array of accelerometers mounted on the mill lifter bolts linked to a fast data acquisition system which monitored the surface waves generated during operation. Details of the system are presented. Mill operating variables were adjusted systematically to provide a wide range of operating conditions for surface vibration signal collection. The experimental approach is discussed.The signals acquired during the experiments were analysed using a range of techniques. The results show that strong relationships exist between measured vibration power (both total power and within certain frequency bands) and mill load level/power and mill speed. A new method for extraction of power spectral density and band power information on features of interest in a mill rotation cycle is also presented.These results show that single sensor analysis information from the surface vibration system can be used as soft sensor inputs for monitoring process variables such as mill load that until now, have not been reliably measured. System outputs also show considerable promise in the area of condition monitoring. An example of the signal analysis output is presented showing elevated vibration levels in an area with higher resultant wear. Eventually, it is considered that outputs from this system for process variable and wear condition monitoring will be key new inputs to an online AG/SAG mill monitoring and control system."

Jan 1, 2003

The major components of sylvinite ores, sylvite (KCl) and halite (NaCl), are separated by flotation. Since both these minerals are water-soluble, the process is carried out in a saturated brine, 6~7 mol/L aqueous solution of NaCl and KCl. C16~C22 primary amines, utilized as a collector, are practically insoluble in water. In commercial potash ore flotation operations these amines are melted by heating up to 70~90°C. They are then neutralized with hydrochloric or acetic acids, and such a hot emulsion/dispersion is introduced to the flotation pulp (which is at room temperature). This is immediately accompanied by the appearance of a white precipitate in the system. As our measurements indicate, the Krafft point of dodecylammonium chloride in concentrated electrolyte solutions is much higher than 80°C, and the Krafft point of C16~C22 amines is substantially higher than that. Introduction of a hot amine emulsion into a pulp, at temperature much lower than the Krafft point for the utilized amines, must cause precipitation of the amines. Some of these species are obviously flotation-active. It is interesting to observe that in summertime, when temperatures are high-er, longer chain amines perform better. It demonstrates that the colloidal amine species that precipitate serve as active species in the potash flotation. Therefore, at higher pulp temperatures, when the temperature difference between the pulp temperature and the Krafft temperature of the utilized amine is not sufficiently large, a longer chain amine, the amine with a higher Krafft point, is more efficient. The results reveal that premixing of an alcohol such as MIBC (common frother) with the amine significantly improves flotation performance of the amine. In the presence of such an alcohol the amine disperse system becomes less turbid, and the rheology of the system less non-Newtonian. All this indicates that MIBC, which does not operate as a frother in a potash flotation system, when used as a co-surfactant, enhances the dispersion of the amine colloidal system. The appearing colloidal species perform as an active form of the collector.

Jan 1, 2014

By M. M. Moghaddam

Charge motion is of prime importance in the efficiency of comminution in tumbling mills. Since direct observation of charge shape and its motion in industrial mill are not possible, a combination of analytical and physical studies was used to determine charge trajectory. Software packages, which predict charge motion such as the GMT (Grinding Media Trajectory) only consider the outermost layer of charge (single ball) and ignore the interactions of grinding elements. In this research, the measured charge trajectory in a 1m-diameter mill with the transparent end, called model mill, was compared with that of the GMT. Four types of polyurethane rings were accurately machined to scale down the liners arrangements at two industrial mills. To explore various charge shapes and trajectories, the model mill was operated at 55, 70 and 85% of critical speed for five levels of mill filling (10, 15, 20, 25 and 30% by volume). The angular displacement of the toe, toe departure, shoulder and charge impact point were determined from the photographs taken from the model mill. New relationships to predict charge shape and charge impact points were introduced to modify the GMT results. The relationships were validated by the model mill using the new liner of the Sarcheshmeh copper complex SAG mill. The relative error of prediction was found to be 1.1%. The results indicated that when the lifter face angle increased from 7 to 30º, the distance between the charge impact point and the toe decreased from 52 to 31º for 25% filling. This meant increasing the probability of charge impacting the toe not the liner which favoured more efficient comminution practice. After converting AG mills to SAG mills on account of liner profile change, 31% increase in throughput (from 419 to 548 t/h) in addition to 4% decrease in the product size (from 516 to 496 µm) were realized which was a significant contribution in the plant performance improvement.

Sep 1, 2012

By Gökçe Törenli, Okay Tutar

"Predicting the performance of plant-scale comminution circuits is essential to monitor the energy use and product size distribution, allowing us to control and optimize the whole process. In the light of this issue, with the assist of recent technologies, simulation techniques utilize the chance of putting the theory into practice in the most accurate way. For this purpose, this study aims to evaluate and optimize the efficiency of a plant-scale ball mill circuit by using perfect-mixing ball mill model on a simulation environment. The comminution circuit is selected from a specific copper-ore processing plant in Turkey. The essential parameters which are required for this study such as fresh feed Bond work index, size distribution etc. are determined by laboratory experiments. The forecasted data which are calculated by third-party software will be compared by the industrial operating data, in order to determine the performance of comminution circuit. In addition to that, this methodology provides a greater ability to analyse, optimize and understand the comminution circuit of ore treatment plant. The authors believe this work will provide supplementary data for further studies on simulation and subsequent optimization of comminution circuits.INTRODUCTION By the assist of mathematical models of the grinding mills and classifiers, simulation of the grinding circuits become more common in comminution because it is relatively economical and able to consider many variables simultaneously. It’s proceeds depends on the accuracy of the models and capability of reflect real operations. Computer-based simulation studies would provide the quantified information about the effects of the proposed changes on the comminution circuit performance in terms of size distribution, mass flow rates, equipment efficiency etc. Then the mentioned data used in order to check the suitability of the current equipment to the modified conditions, and for equipment selection. The outputs of circuit could also be used to estimate downstream flotation circuit performance because the general aim in this study is to The aim of the study is to investigate optimum operating variables and achieve p(80) size of 57 µm and 64 % of -36 µm particle in hydrocyclone overflow stream, which is optimum for that porphyritic copper ore for best concentrate recovery after flotation process in specific copper ore comminution circuit by using modelling and simulation techniques. Sampling survey was carried on the fine ore bin in order to perform Bond work index test and determine work index value (Wi). Thereafter mass balancing, using the size distribution data and tonnages, models for ball mills and hydrocyclone were developed. Finally, the circuit performance were investigated by computer simulations via JKSimMet software."

Jan 1, 2018

By Peng Qian, Xiao Li, Guoyan Fu, Peiwei Han, Yongliang Wang, Shufeng Ye

"Arsenic removal from high arsenic gold concentrate is conducive to increase the mineral value and realize the mineral comprehensive utilization. This study investigated the alkaline pressure oxidation leaching (APOL) of an arsenical gold concentrate in lower temperature to separate the arsenic into filtrate. The effects of temperature, NaOH concentration, solid-liquid ratio, reaction pressure and stirring speed on the leaching efficiency were investigated, and the characteristics of the gold concentrate and leaching residues were evaluated using XRD and SEM analysis methods. The obtained results showed that by using lower temperature (<60?) it is possible to avoid the production of elemental sulfur during the leaching process, which is benefit for the oxidation of arsenopyrite; When the reaction was carried out under appropriate conditions, more than 98% of the arsenic will be extracted into the filtrate as the form of arsenate or thioarsenate. INTRODUCTION In recent years, there has been considerable interest in the recovery of gold from refractory arsenical gold ore. The arsenic in this kind of ore usually exists as the form of arsenopyrite, and the gold surrounded by arsenopyrite exists as the form of fine particles, which will give many difficulties to metallurgical work. When the content of arsenic in the gold ore is more than 0.5%, it will seriously penalize the smelting efficiency (Ruiz et al., 2014). So pretreatment of the refractory gold ore is necessary to obtain the largest economic value and environmental benefits (Balaz et al., 2000). The oxidation pretreatment processes mainly include roasting oxidation, pressure oxidation, chemical treatment and biological treatment (Ann et al., 1992; Kou and Chen, 2012; Tongamp et al., 2010; Fernandez et al., 1995; Lin and Zheng, 1996). Among them, the roasting oxidation and pressure oxidation are the more ordinary processes in industry. The roasting oxidation process is the mature and adaptable technology, but the production of waste gas containing sulfur and arsenic will pollute the environment. The pressure oxidation method possesses certain metallurgical and environmental advantages, and can efficiently decompose the mineral. According to the different solution media, the pretreatment can be divided into alkaline and acidic pressure leaching pretreatments (Papangelakis and Demopoulos, 1990; Hiskey and Sanchez, 1995). The acidic pressure oxidation method has been used in most smelting plants for high arsenic gold ore pretreatment, while the alkaline pressure oxidation is still not widely applied. Compared with the acidic pressure oxidation, the alkaline pressure oxidation can be realized under lower temperatures."

Jan 1, 2018

By J. H. Zhang

An atomic force microscope has been used to measure the forces acting between two silica and two rutile surfaces in the presence and absence of cationic surfactants, CnTACl (n = 12~18). The forces measured in the absence of surfactant can be fitted to the DLVO theory. At short separations, however, the silica surfaces exhibited repulsive hydration forces, while the rutile surfaces did not. On the other hand, the forces measured in the presence of the cationic surfactants show long-range attractions that are larger than the van der Waals forces. The long range attractions are the strongest at of the point of charge neutralization (p.c.n.), which decreases with increasing surfactant chain length. The possible origin of the long-range attraction has been tested in view of the charged-patch model of Miklavic et al. (1994). However, the sizes of the patches back-calculated from the model were much larger than those the patches (or hemi-micelles) determined experimentally and reported in the literature. It is, therefore, suggested that the long-range attractions observed in the present work are due to the structural response of the water molecules in the vicinity of hydrophobic surfaces.

Jan 1, 2014

By Rhulani F. Maluleke, Francis W. Petersen, John H. Marsh, Johann de T. Steyl, Allan Nesbitt

"Pressure leaching of chalcopyrite and nickeliferrous pyrrotite at temperatures between 105 and 200 ºC has been proposed as a potentially viable route for the extraction of mineral elements from sulphide concentrates. In general, these concentrates contain iron, and the economic success of the processes is partially dependent on the choice of the environmentally acceptable iron-removal technique. One of the most widely used methods for the removal of iron from sulphate liquors is precipitation as hematite, goethite, or jarosite. The nature of the iron precipitate formed dictates downstream dewatering and residue treatment and disposal options. However, a better understanding of iron precipitation under the defined process conditions would consequently be of benefit in process design and optimisation.This study investigated the precipitation of iron in the autoclave at temperatures between 105 and 200 ºC. The effects of temperature, acid concentration, iron concentration, and the presence of other metal cations on the nature and composition of the precipitates were determined."

Jan 1, 2003

By Abhilash

Different methods of utilizing refractory bauxite and disposing red mud are practiced throughout the world, but none of them are known to be environmentally innocuous due to the complexity and /or high cost, and none has been found to be feasible on an industrial scale. Under these conditions, the use of bioleaching process seems promising. The present study emphasizes on the isolation of native extremophiles from the source Indian bauxite and red mud, with their detailed cellular and physio-chemical, and biochemical characterization. These organisms were tested for their ability to thrive in physically or geochemically extreme conditions. The gram positive capsule rich mesophiles and thermophiles were tested for removal of gangue minerals from the bauxite and red mud samples. Keywords: refractory bauxite, red mud, extremophiles, bio-beneficiation, gangue

Sep 1, 2012

By F. Y. Kang

Graphite with layers structure is easily to form graphite intercalation compounds (GICs) by means of intercalation reactions due to the weak cohesion force among carbon layers, van der Waal?s interactions. By controlling the oxidation-intercalation, high quality exfoliated graphite with low residual sulfur content and MClx-GICs (M=Fe, Co, Ni, Cu, Zn) powder for electromagnetic wave absorbing and shielding materials have been invented. The expansion volume of expandable graphite can be larger than 160 mL/g while the residual sulfur content is less than 800 ppm. The MClx-GICs powder can shield infrared ray and laser completely up to 15 min. We have also in-vented exfoliated graphite for heavy oil adsorption and mild-expansion exfoliated graphite for anode materials in lithium ion battery by controlling the intercalation/de-intercalation. The exfoliated graphite can adsorb heavy oil up to 80 g/g, it also exhibits better performance than commercial active carbon in sewage treatment. The mild-expansion exfoliated graphite as anode material shows high capacity of 370 mAh/g and good cycle performance.

Jan 1, 2014

By J. Seo, W. Kim, I. Bae

"Microcrystalline silica impurities such as quartz and opal-CT commonly associated in bentonite should be controlled and removed as far as possible when bentonite is used as biocompatible raw material because they show sufficient evidence of carcinogenicity. Since opal-CT contained in bentonite in trace amounts cannot be well separated by conventional sedimentation method, in this work, the ultrasound-assisted removal of the impurity was attempted. Irradiating ultrasound into bentonite-water suspension promoted the production of fine montmorillonite particles in the suspension and the production markedly increased when montmorillonite was activated by Na2CO3. Subsequent centrifugation of the suspension made it possible to recover pure montmorillonite particles as an overflow product. Only 16.2 mass % of total solids was recovered as an overflow from the non-activated suspension, whereas 63.5 mass % was recovered from the activated suspension at centrifuging speed of 10000 rpm. Increasing sonicating time enhanced the yield of overflow, however, excessive sonication up to 10 min hindered the purification of montmorillonite. It was observed that the peak reflection of (101) plane of opal-CT in overflow increased as sonicating time increased during prolonged sonication. INTRODUCTION Bentonite consisting predominantly of mineral montmorillonite is clay-rich soft rock generated frequently from the alteration of volcanic ash. Depending on the nature of its genesis, bentonite contains a variety of accessory minerals, which may include mainly quartz, feldspar, opal cristobalite/tridymite (opal-CT), calcite, illite and mica. The presence of these accessory minerals can impact the industrial value of the deposit, reducing its commercial value depending on its applications. Therefore, bentonite is often purified by removing these impurity minerals for special applications where specific properties and characteristics are required (Murray, 1999). Among the special applications, bentonite is often used in the cosmetic and pharmaceutical industry as both excipient and active ingredient in the forms of liquid (suspensions, emulsions), semi-solid (creams, ointments) and solid (powder, capsules and tablets). The basic requirements for bentonite to be used as raw material are pure, microbiological and mineralogical inertness. Physical properties such as swelling volume and gel formation are also important. Particularly, microcrystalline silica polymorphs such as quartz, cristobalite and opal-CT should be controlled and removed as far as possible because they show sufficient evidence of carcinogenicity in humans."

Jan 1, 2018

By Brian Lindner, Lidia Auret, Niel Knoblauch

In this paper, a fault detection and identification framework based on feature extraction and topology extraction methods is proposed, and evaluated on a simulated base metals refinery high pressure leaching process. Feature extraction methods included linear and kernel principal component analysis, while process topology information was extracted with linear cross-correlation, partial cross-correlation and transfer entropy. Connectivity maps were constructed to identify possible fault propagation paths to aid root cause analysis. The results indicate that process topology can enhance the fault identification capability of data-based process monitoring methods. The study of the considered base metals refinery pressure leaching process is ongoing, with future work including the creation of a fault library which would lead to further critical evaluation of the proposed fault detection and identification framework.

Jan 1, 2014

By M. D. Amirova

Cyanide-free technology of complex copper-lead ores flotation may be improved through enlarged range of pH values, enhanced copper recovery into copper concentrates due to additional recovery of secondary copper sulfides, as well as through enhanced efficiency of lead sulfides depression in process of new flotation modifiers-based selective separation. Study of the effects of flotation modifier (of metal nature) on minerals surface conditions proved that the xanthate is practically not adsorbed on the galenite surfaces due to minerals hydrophilization. Joint effects of sodium sulfite and modifier enhance process conditions for intensive galenite depression and at the same time for effective chalcopyrite and chalcosine flotation within a large pH values range (from pH=8 to pH=10). Identified mechanisms carry inference that proposed chemical reagent treating method is very promising for selective copper-lead concentrates separation. Potential use of carbon-containing materials as zinc flotation modifier to enhancing zinc recovery in processes of lead-zinc ores treatment has been studied. In our flotation tests we used Shalkiya (South Kazakhstan) lead-zinc ores containing such impurities as carbon shales, which presence impedes the process of saleable concentrates production and gives rise to excessive consumption of flotation agents due to the xanthate adsorption on the carbon. Lead and zinc concentrates were produced by process stages as follows: ores milled to 95% Cl. -0.074 +0; lead and zinc roughing flotation and further recleaner and testing operations. Test flotation in open process cycle resulted in enhancing zinc recovery into zinc concentrates by 21.1% and increasing zinc content in zinc concentrates by 3.96% that evidences promising potentialities for use of carbon-containing products as additional zinc flotation modifier. Works were carried out under National Program 2003~2005 of fundamental researches ?Physical and Chemical Mechanisms of Interactions in Multicomponent Solid and Liquid Systems Specific for Integrated Processing of Complex Metal-Containing Minerals and Technogenic Raw Materials? and contractual Agreement 2005 Optimization of Production and Technology of Shalkiya Lead-Zinc Ores Processing at Kentau Dressing Works.

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 E. Scheepers

Within a phosphorus producing submerged arc furnace it was found that the continuous fluctuation of the furnace between a flowrate-driven state (high throughput) and a thermodynamic-driven state (low throughput) caused both techniques to have similar overall, predictive abilities and resulted in a linear, ARX-type, adaptive prediction model as the model of choice. Secondly, this pre-diction model was developed, tested and then shown to have a reasonable, 8-hour-ahead predictive accuracy (R2, coefficient of determination) of 30% (±6%) on future Pslag values. This inherent relationship exists because, at the precise moment of a Pslag prediction, the furnace already contains the metallurgical memory (input variables to the linear model) needed to ensure that some predictive possibilities will always exists - all as a result of the long residence times in the furnace. Residence time, however, is not a directly adjustable variable but rather a fully dependent variable and a function of an array of interconnected and interactive variables. In fact, this applies to virtually all input variables, reemphasising the importance of innate metallurgical memory. Thirdly, predictive control possibilities were explored by simulating the set-points of two fully independent variables used by operators to control the process: the ratio of fixed carbon-to-P2O5 and the ratio of silica gravel-to-pellets. This linear, predictive control model showed only a slight improvement with an 8-hour-ahead predictive accuracy of 35% (±7%). This highlights how ineffective current adjustments are in optimally steering the process and how difficult even incremental improvements in feed-forward and predictive control can be. Finally, it is shown that fundamental design-, sampling- and process restrictions currently associated with the process will always limit the predictive and especially control accuracy or meaningfulness of any dynamic model. These restrictions include the size of the furnace resulting in long residence times, 8-hours sampling intervals, an extremely complex and interactive process and a 16% spatial analyses variation on the Pslag values ? the very value that the model is to predict. The point is made that, given the current status quo, even the perfect dynamic prediction model can not improve on an 8-hour-ahead prediction of 30% (±6%). This barrier can only be pierced with e.g. tidier and more frequent sampling regimes and other upfront capital investments, a decision that becomes a cost accounting exercise and that can only be taken by the management structure. An investment demanding ever-increasing attention is CFD software and it?s potential to shed more light on the complex interactions within the furnace.

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 G. Y. Liu

The structure-activity relationships for four thionocarbamate collectors are discussed in this pa-per. These collector classes are alkyl alkyl thionocarbamates, allyl alkyl thionocarbamates, acyl al-kyl thionocarbamates and alkoxylcarbonyl alkyl thionocarbamates. The main emphasis will be to highlight the differences between collectors and their affinities for copper and iron sulfide minerals on the basis of data on electronic-structure properties obtained by vacuum and solution density functional calculations, flotation experiments and analysis measurements. The mechanism of interaction of these collectors with sulfide minerals is also discussed with perturbation theory. The theoretical study results indicate that acyl alkyl thionocarbamates and alkoxylcarbonyl alkyl thionocarbamates have best performance in these agents as flotation collectors with improved collecting power for copper sulfide minerals and excellent selectivity against iron sulfide minerals, which are consistent with the experimental data reported in the literature.

Jan 1, 2014

By J. J. Lui

Surfactant plays a critical role in many industrial processes such as petroleum, mining, environment and food processing, and daily life. For ionic surfactant systems, adsorption of surfactant at oil-water interface imposes a net charge to the interface. The nature and magnitude of the charges at the oil-water interface depend on charge characteristics of surfactant molecules, concentration of surfactant and solution pH. In our previous study, zeta potential measurement of hexadecane drop-lets in industrial process water was shown to be a simple, yet powerful method for identifying various types of ionic surfactants present in the aqueous system. In this paper, the site-binding model was applied to prediction of zeta potential of oil droplets in aqueous solutions containing a mixture of cationic and anionic surfactant molecules. The total number of interfacial sites for various types of surfactant involved was determined by applying the Gibbs adsorption equation to the measured interfacial tension-surfactant concentration profiles. The distribution of various types of surfactant molecules at the interfaces was evaluated by Langmuir isotherm constants. With the ionization constant of surfactant taken from the literature, the predicted zeta potentials of oil droplets in surfactant solutions from site binding model were shown in a reasonable agreement with the measured zeta potential values.

Jan 1, 2014

By E. Kusaka, M. EL Salmawy

"The electrokinetic behavior of EL Maghara coal has been investigated in the presence of nonyl and octyl nonionic surfactants containing polyethoxy of different sizes with trade names of Triton-X100 (TX-100), Triton-X 705 (TX-705), Triton WR-1339 (TWR-1339) and Brij 58. The electrokinetic behavior was determined by zeta potential measurements. Zeta potential measurements were conducted by Laser-Doppler electrophoresis technique using zetamaster. The results show that the zeta potential of Egyptian coal varies with pH value, the hydrocarbon chain and number of ethoxy groups in the hydrophilic group of the surfactant. It was found that the polymeric surfactants reduce the negative values of zeta potential of coal. The shift of PZC of coal upon deashing appears to be closely relevant to silicate mineral removal."

Jan 1, 2014

By P. Huang, D. W. Fuerstenau

Various factors that control the natural flotability of talc, including differences due to crystal face and edge effects, were delineated. For study of talc depression phenomena, dextrin was used as a model depressant. For the enhancement of talc flotation, dodecylammonium acetate (DDAA) was used as the collector. The interaction of DDAA with talc was assessed by flotation experiments and electrokinetic (zeta potential) measurements, from which the role of hydrophobic bonding can be demonstrated. The results presented in this paper provide useful information on how the crystal chemistry and surface chemistry control the electrical double layer, adsorption phenomena, wettability, and flotation behavior of talc in aqueous media.

Jan 1, 2003