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By M. Kargar Razi

According to the unique properties and many applications of nano gold powder, it was prepared from an acid leaching tail solution. The low value residual gold ions were existed in acid leaching tail solution in Mouteh gold mine in Iran with fellow heavy metals as pollutants (FeP2+P, Cu P2+P, and ZnP2+P). Preparation of nano gold particles is achieved by two steps. First, by addition of ammonia as separation step and second using suitable reagents for precipitation/extraction step. Conditions control includes pH, residence time, temperature, agitation, and molar ratio of reducing agents to reagents. The optimum results show that nano gold powder was prepared by temperature of 250 °C, urea to gold molar ratio of 3:1, and reduction time of 20 min. Also, heat treatment improves dispersion of nano sized gold particles. The properties of gold nano powders were evaluated by SEM, A.A, and UV- Vis spectroscopy methods. The size of prepared particles were about 80nm to 90nm.

Jan 1, 2014

By C. Gomez, J. Finch, R. Dalhke, J. Torrealba-Vargas

The velocity of gas passing through a flotation cell can be estimated by collecting bubbles by natural buoyancy in a closed tube and measuring the rate of pressure increase. The governing equation is derived and verified. Single- and two-tube gas velocity sensors are described. The latter design permits a correction for bulk density and level change during signal collection.

Jan 1, 2003

By M. S. Eygi

This study covers the investigations based on the electrokinetic and rheological properties to explain the interactions between kaolin minerals and commercially available polyelectrolyte in anionic character. Additional adsorption test were also conducted to support the interaction mechanism. Adsorption tests showed that adsorption densities decrease by increasing the solid content. In-creasing the solids contents from 1% to 30% by weight resulted in the decrease on adsorption from 2.14 mg/g to 1.85 mg/g. Because of its difficulty, the solids ratio at 70% was not studied. However, following to trend of the curve plotted adsorption density-solid ratio, an estimation was made and adsorption density at 70% solid content was extracted from the curve as 1.75~1.80 mg/g. The electrokinetic studies pointed out that the presence of polyelectrolyte increase the zeta potential of kaolin from 40 mV to 60 mV which is reasonable conditions to disperse and stabilize the kaolin slurry and lower the viscosity. When these result of the different tests are combined and considered together, 2 mg/g polyelectrolyte concentration was noted as optimal concentration where adsorption density, viscosity and zeta potential of the slurries give maxima and remain constant after this concentration.

Jan 1, 2014

By T. Ueda, T. Oki, S. Koyanaka

"Accurate assessment of the liberation state of crushed ore particles is important for efficient mineral processing. In general, the liberation state is assessed by two-dimensional (2D) measurement of polished ore sample sections. However, this 2D measurement inevitably suffers from overestimation of the degree of liberation, known as stereological bias. This arises from the fact that biphase particle sections of which only one phase happens to have been cut are indistinguishable from liberated particles. To date, several stereological correction methods have been proposed, but their applicability for various types of particles has not yet been sufficiently examined, and this tends to undermine their practicality. We have addressed this problem using a numerical-analytical approach in which various types of biphase particles are modeled, and the 2D sectional information is compared with actual three-dimensional (3D) information. Through simulations, we revealed a general relationship between the internal mineral structure of particles and the stereological bias. Finally, we have developed a unique stereological correction method in which the texture (a 2D pattern characteristic) of particle sections is used to estimate the internal structure of particles, and thereby the stereological bias. KEYWORDS Mineral liberation, stereological bias, texture analysis INTRODUCTION Mineral liberation assessment of 2D particle sections inevitably suffers from stereological bias; that is, overestimation of the degree of liberation. Stereological bias is caused by the fact that a composite particle can be misidentified as a liberated particle when only one phase happens to have been cut in sectional measurement. Stereological bias has attracted attention since Gaudin pointed out its importance in 1939 (Gaudin, 1939). Several attempts have been made to measure the 3D liberation state directly, avoiding the bias, using X-ray computed tomography (Gay and Morrison, 2006; Lin and Miller, 1996; Miller et al., 2003; Miller et al., 2009; Reyes et al., 2017; Videla et al., 2007). These have provided useful information through laboratory testing, but further technical refinement is necessary for practical usage, to overcome the technique’s limitations in terms of resolution, assessment of minerals of similar density, and speed. Therefore, for practical purposes, detailed information regarding mineral phase geometry is obtained by sectional analysis, using automated scanning electron microscopy/energy-dispersive X-ray spectroscopy (SEM/EDX)-based analysis (e.g., with a mineral liberation analyzer (MLA) (Fandrich et al., 2007; Sandmann, 2015)); and the development of an effective method of stereological correction, which predicts the relevant bias and transforms the measurable 2D degree of liberation into its 3D counterpart, is an important research aim."

Jan 1, 2018

By Y. M. Zhu, G. C. Gong

"The influences of citric acid (CA) on the flotation behavior of cassiterite using styrene phosphonic acid (SPA) as the collector were studied via single mineral flotation tests, contact angle measurements, zeta potential determinations and solution chemistry calculations in this paper. The results of single mineral flotation tests revealed under the conditions that pH=4 and the dosage of SPA 100 mg/L, the recovery of cassiterite reached 76.78%. The addition of 20 mg/L AC decreased the recovery by 12.42% at pH=4. Contact angle measurements demonstrated the adsorption of CA prior to SPA made the cassiterite more hydrophilic. The results of zeta potential determinations and solution chemistry calculations indicated the chemisorption of C6H7O7- and C6H6O72- filled parts of the Sn site on cassiterite surface and prevented the SPA from getting adsorbed. The hydrophilic effect of AC was stronger than the hydrophobic effect of SPA and the flotation of cassiterite was crippled. INTRODUCTION Tin is an important metal which is widely used in medical instruments, marine engineering materials, electronic and electrical devices, welding, weapon manufacturing and organotin compounds industries (Angadi et al., 2015). Cassiterite is the only mineral from which the tin can be extracted, thus it is of great importance to efficiently exploit the cassiterite mineral. Flotation is an indispensable method for the recovery of cassiterite (Li et al., 2015). However, cassiterite is usually in association with many other gangue minerals which are of similar floatability, such as quartz, calcite, fluorite, iron oxide, wolframite, scheelite and tourmaline (Sreevinas, 1997). So some modifiers are necessary in the cassiterite flotation process. The amounts of the modifiers used in the flotation must be judicious and the overmuch modifiers may cripple the recovery of cassiterite (Parsonage et al., 1987). Nevertheless, the research about the effects of the modifiers on the flotation behavior of cassiterite has been rarely reported. In this paper, the influences of citric acid (CA) on the flotation of cassiterite using styrene phosphonic acid (SPA) as the collector were investigated by flotation tests, contact angle measurements, zeta potential determinations and solution chemistry calculations."

Jan 1, 2018

Due to complex mineralogical and chemical interactions of the value and gangue mineral phases present in uranium-containing lateritic ores, deleterious pulp gelation which impacts on value metal recovery sometimes occur during atmospheric leaching. In this study, the leaching behavior and particle interactions of selected oxide (hematite, quartz) and clay minerals (muscovite, chlorite), which constitute predominant host gangue phases of typical lateritic uranium ores are investigated to provide basic, mechanistic understanding of temporal pulp gelation phenomenon. Isothermal, batch leaching with H2SO4 was carried out on concentrated dispersions (30 ? 57 wt.%) of single minerals at pH 1 and 25 or 70 °C and their concomitant solution, speciation and rheology (shear yield stress, viscosity) were characterized. It is clearly shown that despite the high oxide content of lateritic ores, the pulp chemistry and rheology is largely affected by the incongruent leaching behavior of more reactive, acid-consuming aluminosilicate clays. Furthermore, time- and temperature-dependent alumino-silicate species polycondensation interfacial reactions are shown to be responsible for the enhanced particle interactions, reflecting strong pulp rheology in agitation and pumping. If not properly mitigated, high pulp shear yield stress and viscosity have a striking impact on processability and hence, value metal recovery.

Sep 1, 2012

By B. McFadzean, J. Taguta

The enthalpy of immersion is the heat change arising from the replacement of the solid-gas interface with the solid-liquid interface when a solid surface is immersed in a liquid. Although immersion calorimetry has been established as a valuable and reliable means of determining solid surface properties such as wettability, it has seldom been applied in mineral processing research. In this study, precision solution calorimetry was employed to measure the enthalpies of immersion of different minerals in water. The enthalpies of immersion were then related to the first-order flotation rate constant as determined by the microflotation technique. The same measurements were also made on sulphide minerals whose surfaces were modified to different degrees of hydrophobicity using different percentage coverages of amyl xanthate collector. The enthalpy of immersion technique was capable of distinguishing and ranking minerals according to their wettability. All mineral types and collector-treated minerals conformed to the same relationship that was found between the enthalpy of immersion and the flotation rate constant. This conformed, empirically, to a power law equation. As the enthalpy of immersion decreased, there were large increases in flotation response for very small changes in hydrophobicity. In addition, a critical enthalpy of immersion (CEI) was found, above which no flotation could occur. The scatter in the data points could be corrected for by adjusting the rate constant using the density of the minerals to produce a robust relationship between the rate constant and enthalpy of immersion. These results have shown that the enthalpy of immersion is able to indicate both the natural mineral hydrophobicity and the extent to which collectors can render a mineral hydrophobic. This technique has considerable potential to be used as a sensitive and accurate measure of mineral surface wettability in order to predict flotation performance.

Jan 1, 2018

By X. Q. Wu

Magnetization in slurry (MIS) of weakly magnetic minerals by iron ions was investigated. The magnetic seeds (strongly magnetic particles) were synthesized by ferruginous chlorides directly in slurry instead of previous preparations of magnetic seeds by finely grinding mineral magnetite or specially synthesizing them separately in an aqueous solution. In this way, the growth of the seeds and their adsorption on the minerals simultaneously take place in the same slurry. That after MIS the recovery of weakly magnetic mineral limonite in a magnetic separator increased means the formation and adsorption of magnetic seeds on the surface of iron mineral limonite. The magnetization effect was evaluated by limonite recovery at a magnetic strength of 3.500 Gs in a magnetic separator. Mineral limonite was properly magnetized in the following slurry condition: molar ratio of Fe3+ to Fe2+1:3, slurry temperature of 45 °C and pH 10.5. The selectivity of the magnetization between minerals limonite and quartz was improved by adding surfactant sodium oleate.

Jan 1, 2014

By S. Banisi, O. Farshid, M. R. Rozebehi, A. Bahar, A. Arghavani, M. Mahdavi

At the rougher flotation circuit of the Miduk copper concentration plant (Kerman, Iran) five column cells (CISA) with the diameter of 4m and height of 12m using static mixer type (MicrocelTM) spargers have been installed. Based on the initial design, columns should accept a feed rate of 625 t/h with 80% passing size of 90 µm and solids concentration of 28% and produce 88% of the plant concentrate (i.e., 22 t/h) containing 32% copper. Due to mechanical and processing problems this objective was never realized and theses columns were remained out of operation from the commissioning time (2005). A new attempt with the aim of returning these cells into operation started in 2013. The results of an extensive study indicated that spargers plugging due to the entrance of small amount (2 kg) of coarse particles (up to 2.5 cm) because of usual problems at the plant environment was the main reason of columns non functionality. With a change in the recycle pump inlet design to the column, which prevented the entrance of coarse particles to the spargers, the operation of the column significantly improved. It was found that in order to have a stable operation of the columns at the rougher stage the feed rate for each column should be reduced from 125 (design) to 70 t/h. The air superficial rate had to be also reduced from 1.9 (design) to 0.6 cm/s. A period of 10 days of continuous operation showed that the carrying capacity was 0.23 (g/min/cm2) which was significantly lower that of the design value (i.e., 0.58). The gas hold up was found to be lower than 10% beyond which columns started to move to the turbulent state indicated by "boiling" froth. The average life time of spargers was determined to be 20 days which considered to be very short. The average recovery and concentrate grade of these columns were found to be 68% and 32%, respectively. The high wear rates of spargers, unusually high level of maintenance and supervision needed and instability of the operation made the plant managers not to use column cells as the roughers.

Jan 1, 2014

By A. Buchanan, M. Mirnezami, A. L. Restrepo, J. A. Finch, M. S. Hashemi

Settling rate studies on slurries from Cu/Zn flotation plants occasionally revealed two aggregation maxima at pH 8-10 and 10-12. From measurements on sphalerite and silica suspensions the double maxima were replicated by Zn ions (pH 8-10) and Mg ions (pH 10-12) corresponding to the presence of zinc hydroxide and magnesium hydroxide, respectively. A combination of chemical and electrostatic bridging by the hydroxides is considered to be the aggregation mechanism.

Jan 1, 2003

By David De Klerk, Maximilian Richter, Thirunavukkarasu Pathmathas, Indresan Govender

We consider the average power dissipation distribution for dense granular flows of an idealised mono-sized charge (5 mm glass beads) in a 300 mm diameter tumbling mill operated in the cascading-to-cataracting Froude regime. By combining the inherent frictional nature of particles within a dense flow regime and noting that tumbling mills are typically characterised by collisional and turbulent stresses, we derive the power dissipation distribution for athermal boundary conditions. The input data to the model (velocity, solids concentration, pressure and flow depth) are obtained directly from non-invasive measurement using a nuclear imaging technique: Positron Emission Particle tracking (PEPT). The power dissipation due shear stresses is shown to be the dominant mode of dissipation in the tumbling mill with up to two orders of magnitude difference between pressure induced dissipation and shear.

Jan 1, 2014

By E. A. Brocchi

This work is dedicated to the chemical treatment of a typical EAF dust by chlorine content agents. The residue contains 48% Fe2O3 and 28% ZnO mainly in the franklinite structural form. The others less compounds are: 4.00% CaO, 2.60% MnO, 2.20% MgO, 1.08% PbO, 0.36% Cr2O3, 0.21% B2O3, 0.03% CdO and 0.01% NiO. The experiments purpose is selectively to remove zinc from the residue leaving the iron behind. Thermodynamics studies have indicated some roasting possibilities. The experimental results have shown that both HCl leaching and carbochlorination will remove iron and zinc without any selectivity. However, either the chlorine or the calcium chloride roasting seems to form, preferentially, the zinc chloride. So, it will be presented how the EAF Dust can be treated by the using of chlorine roastings process such as carbochlorination in order to separate the zinc and iron present in the frankilinite, main EAF dust content.

Jan 1, 2014

By Chen Jianhua, Shen Zhenchang, Zhang Ming, Chen Feifei

"With flotation cells scale-up, the performance of flotation cells is increasingly variated for short-coming and dead zones existing. The residence time distribution which shows the movement of tracers can assess the unexpected flows such as short circuit and dead zone in a flotation cell. In this paper, the residence time distribution of pilot flotation cell is investigated with CFD simulation. Based on the theoretical model, the short-coming probability and dead zone probability are quantitative. The ideal average residence time is similar with the actual average residence time. The mixing effect of the flotation cell approaches the ideal continuous stirred tank reactor. The operating parameters such as speed and feed velocity have complicated influence on residence time distribution. The research would be helpful to understanding flow in flotation cell and improving performances of flotation cell.INTRODUCTION Froth flotation is a method which purifies minerals according to difference of physical and chemical surface characters of different mineral particles (Shen, Z., Chen J, 2012). Flotation cell is a key equipment for froth flotation method. The flotation cell performances have great influences on flotation index.It is difficult to evaluate flotation cell how to improve flotation procedure to complexity. The main flotation cell performances are aeration volume, air dispersion, solid suspension and residence time distribution, etc (Shen, Z., Lu, S., 2008). Residence time distribution is an important fluid hydrodynamics which could reveal the flow of pulp, mixing of particles and air bubbles. In the flotation cell, the ideal average residence time of pulp could obtain easily. But the fluid differential units would be different flow paths. The residence time of the fluid differential units is variation and would be longer or less than the average residence time. The residence time distribution would reveal the mixing effect and predict the not ideal flow in the flotation cell such as shorting cutting, dead zone, etc. As we know, the shorting cutting and dead zone would be decreased the real flotation time and it is disadvantage to better flotation effect, especially for large flotation cell. It is impossible to eliminate the not ideal flow totally. It is very important to reveal and decrease the shorting cutting and dead zone probability in the flotation cell."

Jan 1, 2018

By Chen Jianhua, Shen Zhenchang, Zhang Ming, Chen Feifei

"With flotation cells scale-up, the performance of flotation cells is increasingly variated for short-coming and dead zones existing. The residence time distribution which shows the movement of tracers can assess the unexpected flows such as short circuit and dead zone in a flotation cell. In this paper, the residence time distribution of pilot flotation cell is investigated with CFD simulation. Based on the theoretical model, the short-coming probability and dead zone probability are quantitative. The ideal average residence time is similar with the actual average residence time. The mixing effect of the flotation cell approaches the ideal continuous stirred tank reactor. The operating parameters such as speed and feed velocity have complicated influence on residence time distribution. The research would be helpful to understanding flow in flotation cell and improving performances of flotation cell.INTRODUCTIONFroth flotation is a method which purifies minerals according to difference of physical and chemical surface characters of different mineral particles (Shen, Z., Chen J, 2012). Flotation cell is a key equipment for froth flotation method. The flotation cell performances have great influences on flotation index.It is difficult to evaluate flotation cell how to improve flotation procedure to complexity.The main flotation cell performances are aeration volume, air dispersion, solid suspension and residence time distribution, etc (Shen, Z., Lu, S., 2008). Residence time distribution is an important fluid hydrodynamics which could reveal the flow of pulp, mixing of particles and air bubbles. In the flotation cell, the ideal average residence time of pulp could obtain easily. But the fluid differential units would be different flow paths. The residence time of the fluid differential units is variation and would be longer or less than the average residence time. The residence time distribution would reveal the mixing effect and predict the not ideal flow in the flotation cell such as shorting cutting, dead zone, etc. As we know, the shorting cutting and dead zone would be decreased the real flotation time and it is disadvantage to better flotation effect, especially for large flotation cell. It is impossible to eliminate the not ideal flow totally. It is very important to reveal and decrease the shorting cutting and dead zone probability in the flotation cell."

Jan 1, 2018

By Seungwoo Park, Gaurav Soni, Roe-Hoan Yoon, Hyunsun Do, Kaiwu Huang

In a flotation froth (and foam), air bubbles become larger due to coalescence, causing bubble size to increase, bubble surface area to decrease, and hence casing less hydrophobic particles to drop off to the pulp phase below. Thus, bubble coarsening provides an important mechanism by which product grades are increased. On the other hand, excessive bubble coarsening results in low recoveries. In the present work, a model describing the process of bubbles becoming coarser in a foam as they rise to the top by deriving a mathematical relation between the Plateau border area, which controls film drainage rate, and the lamella film thickness, which controls bubble-coalescence rate. The model has been derived by assuming that liquid drainage rate increases due to slip at the air/water interface, and that the critical rupture thickness is determined by the capillary waves created by thermal motion. The model developed in the present work can predict the bubble size ratio between the top and bottom of a foam as functions of aeration rate, foam height, and surface tension (frother dosage). The model predictions are in good agreement with the changes in bubble sizes measured using a high-speed camera.

Jan 1, 2014

By Wenying Liu, Marek Pawlik

Long-chain ionic surfactants, with fatty acids and amines as the most important representatives, are widely used as collectors in froth flotation. These surfactants, generally referred to as weak electrolyte collectors, frequently form solid insoluble precipitates within a certain pH range. However, the action and behavior of these colloidal precipitates in froth flotation systems are not well understood and has not been well decoupled from those of dissolved forms. The objective of this study was to understand and compare the role of colloidal precipitates with that of the dissolved forms at gas-liquid and gas-liquid-solid interfaces. Using primary amine as the model surfactant, experiments were carried out to measure: the maximum volume of bubbles generated in the presence of dissolved and precipitated forms of the surfactant; surface tension for both forms of the surfactant using the drop shape and maximum bubble pressure methods; and contact angle using the sessile drop method. The experimental results showed that: in the presence of the precipitate, bubble volume was smaller, which was correlated with the lower surface tension and higher contact angle measured; the surface tension of solutions containing surfactant precipitate was affected by the surface age of liquid droplets. This study enhances understanding of the interfacial behavior of long-chain ionic surfactants under different conditions, which would help improve the efficiency of reagent utilization in froth flotation.

Jan 1, 2014

Three high-grade limestone ores (CaO content over than 53 %) with different geological origin have been characterized for the synthesis of aragonite precipitated calcium carbonate. Limestone ores examined in this study showed different crystal particle size that cause difference in disintegration degree and surface area of the synthesized slaked limes. The limestone ore with smaller crystal particle size showed higher disintegration degree and also yielded slaked lime with smaller surface area, which is good for the synthesis of aragonite precipitated calcium carbonate. The synthesis of aragonite PCC using the limestone with a small crystal particle size was yielded needle-shaped aragonite with the aspect ratio of about 14. Keywords: limestone, lime, slaked lime, precipitated calcium carbonate, aragonite, accelerated carbonation

Sep 1, 2012

By S. V. Bogdanov, S. I. Grishaev

"The article presents the materials about the appropriateness of the use of rental indices to assess the effectiveness of the use of deposits of rare earth elements (REE). The authors suggest from the standpoint of rent payments to rate for the owner the possibility of using the anticipated rental income as the indicator for the analysis of preferences and economic significance of enrichment of extracted raw materials in the emerging field of rare earth metals (REE). Usually from ore mined at the fields, for flotation technology to produce concentrates with collective REE, then they are subjected to chemical-metallurgical processing of the received products are divided into pure oxides, chemical compounds or isolated from them pure metals and alloys. This commercial product is shipped to the buyer. REE were a non-renewable natural resources, so the calculations for determining differential and specific rent showed that during the development of the technologies of mineral processing of a specific field it is necessary to consider what the expected rental income depends on the magnitude of differential rent is related to the volume of production of REE for the whole planned period of exploitation of natural resources. This income is determined by the amount of stock field. For long-term exploitation of the deposit is observed in almost direct proportional dependence between the annual differential rent and the rental income. The decrease in rents in the long run is determined by the change in the composition of ores included in the extracted raw materials and the balance between light and heavy REE. The largest 70% reduction of the rent projected for ""cerium"" fields, while for ""yttrium"" these losses are considerably smaller. Tomtor, Chuktukon and Katuginskoye Russian deposits are characterized by a level of rent that is comparable to the mastered foreign sources of REE. Thus, the enrichment of minerals with REM in the domestic deposits is quite competitive at the world level. INTRODUCTION Deposits of rare earth metals (REE) are non-renewable resources that should be developed and used so that it would be possible to provide a reduction due to payment of appropriate resources for future generations. This compensation, due to the reduction of natural resources, can be carried out both in natural and in economic terms (1). When analyzing economic compensation options, particular attention should be paid to rental income in assessing the attractiveness of using different REE deposits. It is known that absolute and differential rents are summands when calculating the value of natural rents. The value of the absolute natural rent is proportional to the unit price of the product obtained from mineral raw materials and sold on the commodity market. Limitations, as well as the use in production processes and business, contribute to the gradual reduction of natural resources, which increases their consumer value and affects the price of commodity products from primary raw materials."

Jan 1, 2018

By M. Wright, A. H. Mwale

This paper examines the combination of unit technologies in a minerals beneficiation train, and explores the inter-relationship between energy input and water consumption for a given mineralogy and product recovery, as these are two critical environmental issues which affect the overall viability of many minerals plants. In particular, we review constitutive relationships for each of the sub-processes of comminution, flotation, and tailings dewatering, and suggest how these might be integrated into a unified hybrid model, with particle size distribution as the key design variable. Such a model can then be used to explore the trade-offs between different performance objectives (be these technical, economic or environmental) as part of a multiple-objectives optimisation exercise. In this way, it may become practical to envision situations in which concentrate grade and recovery are sacrificed, marginally, in order to reduce energy demand in comminution, and improve overall water recovery. This becomes more relevant as the industry commits to advancing the sustainable development agenda in the face of the increasing life -cycle costs and impacts of minerals processing operations, coupled to declining ore body grades, and the desire to maximise recovery of minor and trace elements. Some specific observations for copper are offered.

Jan 1, 2003

By S. S. Yu

In this paper, the producing process of using V2O3 as raw material to obtain vanadium nitride was analyzed through the means of thermodynamic. The analysis shows that conversion follows the principle of reduction step by step in the conversion process of V2O3. The temperature of the reaction system has prominent influence on the nitrogen content of products, and the reaction is very sensitive to temperature. As raising temperature, the fine grain structure of the nitrides is more evident, and the grain size of nitrides increases. At 1703K, the nitrogen content of the products tended to be constant after soaking over 3 hours.

Jan 1, 2014