Estimation of Copper and Molybdenum Grades and Recoveries in the Industrial Flotation Plant Using the Artificial Neural Network

In this paper, prediction of copper and molybdenum grades and their recoveries of an industrial flotation plant are investigated using the Artificial Neural Networks (ANN) model. Process modeling has done based on 92 datasets collected at different operational conditions and feed characteristics. The prominent parameters investigated in this network were pH, collector, frother and F-Oil concentration, size percentage of feed passing 75 microns, moisture content in feed, solid percentage, and grade of copper, molybdenum, and iron in feed. A multilayer perceptron neural network, with 10:10:10:4 structure (two hidden layers), was used to estimate metallurgical performance. To obtain the optimal hidden layers and nodes in a layer, a trial and error procedure was done. In training and testing phases, it achieved quite correlations of 0.98 and 0.93 for Copper grade, of 0.99 and 0.92 for Copper recovery, of 0.99 and 0.92 for Molybdenum grade and of 0.99 and 0.94 for Molybdenum recovery prediction, respectively. The proposed neural network model can be applied to determine the most beneficial operational conditions for the expected Copper and Molybdenum grades and their recovery in final concentration of the industrial copper flotation process.

Influence of the roughness and shape of quartz particles on their flotation kinetics

Surface roughness and shape play an important role on the behavior of particles in various processes such as flotation. In this re- search, the influence of different grinding methods on the surface roughness and shape characteristics of quartz particles as well as the effect of these parameters on the flotation of the particles was investigated. The surface roughness of the particles was determined by measuring their specific surface area via the gas adsorption method. The shape characteristics of the particles were measured and calculated by images obtained by scanning electron microscopy via an image analysis system. The flotation kinetics was determined using a laboratory flotation cell. The results showed that the particles of rod mill products have higher roughness and elongation ratio and lower roundness than the parti- cles of ball mill products. The flotation kinetics constant of the particles increased with their surface roughness increasing. Particles with higher elongation and lower roundness indicated higher floatability. In addition, the influence of the surface roughness on the flotation kinet- ics was greater than that of shape parameters.

Estimation of froth flotation recovery and collision probability based on operational parameters using an artificial neural network

An artificial neural network and regression procedures were used to predict the recovery and collision probability of quartz flotation concentrate in different operational conditions. Flotation parameters, such as dimensionless numbers （Froude, Reynolds, and Weber）, particle size, air flow rate, bubble diameter, and bubble rise velocity, were used as inputs to both methods. The linear regression method shows that the relationships between flotation parameters and the recovery and collision probability of flotation can achieve correlation coefficients （R2） of 0.54 and 0.87, respectively. A feed-forward artificial neural network with 3-3-3-2 arrangement is able to simultaneously estimate the recovery and collision probability as the outputs. In testing stages, the quite satisfactory correlation coefficient of 0.98 was achieved for both outputs. It shows that the proposed neural network models can be used to determine the most advantageous operational conditions for the expected recovery and collision probability in the froth flotation process.

黄铜矿精矿在甘氨酸介质中的循环伏安及动电位极化研究

采用循环伏安及动电位极化方法研究黄铜矿在甘氨酸介质中的浸出反应机理及动力学。使用黄铜精矿−碳糊电极研究pH值(9~12),温度(30~90)及甘氨酸浓度(0~2 mol/L)对腐蚀电流密度、腐蚀电位及循环伏安曲线的影响。结果显示,甘氨酸浓度从0增加到2 mol/L导致氧化峰电流密度增加;在相同条件下,腐蚀电流密度从约28μA/cm2增加至约89μA/cm2,同时腐蚀电位由−80 mV降至−130 mV。在温度不高于60℃的条件下,电流密度随温度的增加而增加;当温度高于60℃时,电流密度随温度增加而降低。电流密度随pH值的变化与温度相似,当pH值从9增至10.5时电流密度增加,pH值高于10.5时电流密度降低。此外,铜氧化物及铁氧化物的热力学稳定性在较高温度下增加。

高压电选法从石英中分离锆石的新预处理方法（英文）

静电选矿是一种基于矿物导电性的矿物加工方法。但该方法存在一些严重问题,如对湿度敏感,中矿产率高和含有非导电矿物杂质。为克服这些缺点,本文作者提出一种新的预处理方法,用于在静电选矿前从石英中分离锆石。预处理包括两个阶段:一是使用十二烷基硫酸钠(SDS)作捕集剂调节锆石表面的润湿性,二是喷洒电解质水溶液以提高石英表面的导电性。考察pH值、捕集剂浓度、调节时间、电解质浓度和种类等重要参数对分选效率的影响。研究表明,高压电选的最佳条件如下:pH值为4,SDS浓度为1×10-4 mol/L,调节时间为4 min,NaCl为电解质,其浓度为4.27 mol/L,最佳条件下的分选效率为95.12%。该预处理方法可成功地应用于高压电选前各种组成的导电性或非导电性矿物的分选。

Effect of microwave pretreatment on grinding and flotation kinetics of copper complex ore

The present study initially investigates the kinetics of microwave-assisted grinding and flotation in a porphyry copper deposit.Kinetic tests were conducted on untreated and microwave-irradiated samples by varying the exposure time from 15 to 150 s.Optical microscopy,energy-dispersive X-ray spectroscopy,and scanning electron microscopy were conducted to determine the mineral liberation and particle surface properties,and to perform mineralogical analyses.Results showed that the ore breakage rate constant monotonically increased by increasing the exposure time,particularly for the coarsest fraction size(400μm)due to the creation of thermal stress fractures alongside grain boundaries.Excessive irradiation time(>60 s)led to the creation of oxidized and porous surfaces along with a dramatic change in particle morphologies that result in a substantial reduction of chalcopyrite and pyrite flotation rate constants and ultimate recoveries.We concluded that MW-pretreated copper ore was ground faster than the untreated variety,but the two types have slightly similar floatabilities.

Studies of Grinding Media Corrosion from Galvanic Interaction on Galena Flotation

This study has been done to determine the galvanic interaction between five types of grinding media (mild steel, cast iron, 10% chromium, 20% chromium, and ceramic media) and galena, in situ of the mill. The ceramic media has a significantly not galvanic interaction with galena and high chromium media has a significantly weaker galvanic interaction with galena, and produces a very much lower amount of oxidize iron species in the mill discharge than mild steel medium. The investigation of the various reactions occurring on the galena surface was investigated by ethylene diamine-tetra acetic acid disodium salt (EDTA) extraction and X-ray photoelectron spectroscopy (XPS) measurements. The floatability of galena is dependent on the galvanic current between grinding media and galena during grinding because the current is relative to the amount of iron oxidation species and the reduction rate on galena. Iron oxidation species depressed galena flotation. The optimum galena flotation was achieved by selecting grinding conditions that enabled iron oxidation to be controlled.

Dynamic simulation of the effect of time-dependent variation of pH on response variable of the tailing thickener of coal washing plant

Dynamic simulation approach can be used for understanding the nonlinear behavior in mineral processing circuits. In this study, the gel point, the main parameters of batch flux density function and the main parameters of effective solid stress were determined at different conditions (pH, flocculant dosage and particle size). Therefore, the main parameters of phenome no logical model of sedimentation and thickening were determined as a functio n of particle size, pH and flocculant dosages using the result of experimental tests and Curve expert professional software. Then, the dynamic simulation was carried out for the industrial thickener of coal washing plant and the time-dependent variation of response variables was investigated by time-dependent variation of pH of input feed to thickener using the obtained equations. It was observed that it is possible to predict the thickener behavior as a function of time for time dependent variation of pH of input feed to the thickener of coal washing plant using obtained equations that it was not possible using phenomenological model of thickener alone.

Applied Mineralogical Studies on Iranian Titanium Deposits

Qara-aghaj and Skandian as hard rock titanium deposit and Kahnooj one as a placer deposit were investigated from applied mineralogical point of view. The mineralogical studies were carried out using XRD, XRF, optical microscopy, scanning electron microscopy and microprobe analysis. These studies indicated that ilmenite and magnetite are main valuable minerals in the studied ores. Pyroxene, olivine and plagioclase are the main gangue minerals in Qara-aghaj ore while chlorite and plagioclase are the major gangue minerals in Skandian ore. Plagioclase, clinopyroxene, amphibole, feldspate and some quartz are the important gangue minerals in kahnooj deposit. In all three ores ilmenite is mainly in the form of ilmenite grains but some lamellae of ilmenite with thickness between 0.1 to 20 μm have been occurred as exsolution textures inside magnetite grains, where the magnetite here can be referred to as ilmenomagnetite. In the hard rock ores some fine ilmenites have been disseminated in silicate minerals. The liberation degree of granular ilmenite was determined 150, 140 and 200 μm for Qara-aghaj, Skandian and Kahnooj, respectively. So, only the granular form of ilmenite is recoverable by physical methods. Some sphene and rutile as titanium containing minerals were observed mainly inside ilmenite phase in kahnooj ore. Some fine rutile was also found inside Skandian ilmenite while there were not any other titanium minerals inside Qara-aghaj ilmenite. Apatite is another valuable mineral which was found only in Qara-aghaj ore. Using SEM and microprobe analysis it was found that there are different amounts of exsolved fine lamellae of hematite inside ilmenite in Qara-aghaj and Kahnooj ores while it was not observed in Sckandian one. The average contents of TiO2 in the lattice of Qara-aghaj, Skandian and Kahnooj ilmenite were determined 51.13, 50.9% and 52.02%, respectively. FeO content of ilmenite lattice for all three samples is clearly lower than the theoretical content. This is due to the substitution of Mg and Mn for some Fe2+ ions in the ilmenite lattice. V2O3 content of magnetite lattice is up to 1%. So, magnetite can be a suitable source for production of vanadium as a by-product in all three deposits.

The Empirical Prediction of Gas Dispersion Parameters on Mechanical Flotation Cells

Gas dispersion properties include bubble size ( ), gas holdup ( ) and bubble surface area flux ( ) and input power ( ) are effective parameters on flotation performance. During the last 10 years, some investigations have been carried out to measure these parameters in mechanical flotation cells. In this research, some models are created to estimate gas dispersion properties and input power by experimental data. Variables of models are impeller peripheral speed ( ), superficial gas velocity ( ) and pulp density ( ) and final form of models are , , and . According to these equations, most effective variables are , and , respectively.

Bonded-particle model calibration using response surface methodology

The bonded-particle model （BPM） is commonly used in numerical analysis of the mechanical behavior of rock samples. Constructing a BPM model requires specification of a number of microstructural parame- ters, including the parallel-bond tensile strength, parallel-bond cohesion strength, parallel-bond effective modulus, parallel-bond friction angle, and parallel-bond stiffness ratio. These parameters cannot be eas- ily measured in the laboratory or directly related to either measurable or physical material parameters. Hence, a calibration process is required to choose the values to be used in simulations of physical systems. In this study, response surface methodology along with the central composite design approach is used to calibrate BPMs. The sensitivities of the microparameters related to the uniaxial compressive strength （UCS） and elasticity modulus （i.e., the macroscopic responses of the models） are thoroughly scrutinized. Numerical simulations are performed to carefully assess the performance of the model. It is found that the elasticity modulus is highly correlated with the parallel-bond effective modulus. In addition, the parallel- bond tensile and cohesion strengths are the two most significant microparameters with a considerable effect on the UCS. The predicted values determined by the proposed approach are in good agreement with the observed values, which verifies the applicability of the proposed method.