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Zhang W.,Chinalco China Copper Corporation Ltd | Zhang W.,McGill University
Minerals | Year: 2016

This research is focused on the Phase I SABC milling circuit of the Wushan porphyry copper mine. Improvements to the existing circuit were targeted without any significant alterations to existing equipment or the SABC circuit. JKSimMet simulations were used to test various operating and design conditions to improve the comminution process. Modifications to the SABC comminution circuit included an increase in the SAG mill ball charge from 8% to 10% v/v; an increase in the mill ball charge from 23% v/v to 27% v/v; an increase in the maximum operating power draw in the ball mill to 5800 kW; the replacement of the HP Series pebble crusher with a TC84 crusher; and the addition of a pebble bin. Following these improvements, an increase in circuit throughput, a reduction in energy consumption, and an increase in profitability were obtained. © 2016 by the author; licensee MDPI, Basel, Switzerland.


Zhang W.,Chinalco China Copper Corporation Ltd | Zhang W.,McGill University
Transactions of Nonferrous Metals Society of China (English Edition) | Year: 2014

In operating flotation plants, the viscosity of the pulp can vary significantly. Consequently, the resulting impact on bubble size is of interest as many plants experience seasonal changes in water temperature, or particle size changes as ore hardness, mineralogy and throughput fluctuate. However, given its importance in flotation, there existed no mathematical relationship linking bubble size created in flotation machines to the key process variable of fluid viscosity. In this study, a program of investigation to develop such a model was utilizing a pilot-scale mechanical flotation machine, to investigate the effect of water viscosity due to temperature on bubble size distribution. The bubble sizes were determined using a specific bubble viewer and imaging technology. The temperature itself was varied as a method for introducing significant viscosity change. The viscosity-temperature effect introduced a correspondingly significant change in the water viscosity (1619 to 641 μPa·s). It is suggested that a considerably stronger relationship may exist, yielding D32 versus (μ/μ20)0.776, and hence viscosity becomes an important design consideration for plants operating where pulp temperature fluctuations, very small particles or high solid fractions are present. © 2014 The Nonferrous Metals Society of China.


Zhang W.,Chinalco China Copper Corporation Ltd | Zhang W.,McGill University | Nesset J.E.,McGill University | Finch J.A.,McGill University
Journal of Central South University | Year: 2014

The size of bubbles created in the flotation process is of great importance to the efficiency of the mineral separation achieved. Meanwhile, it is believed that frother transport between phases is perhaps the most important reason for the interactive nature of the phenomena occurring in the bulk and froth phases in flotation, as frother adsorbed in the surface of rising bubbles is removed from the bulk phase and then released into the froth as a fraction of the bubbles burst. This causes the increased concentration in the froth compared to the bulk concentration, named as frother partitioning. Partitioning reflects the adsorption of frother on bubbles and how to influence bubble size is not known. There currently exists no such a topic aiming to link these two key parameters. To fill this vacancy, the correspondence between bubble size and frother partitioning was examined. Bubble size was measured by sampling-for-imaging (SFI) technique. Using total organic carbon (TOC) analysis to measure the frother partitioning between froth and bulk phases was determined. Measurements have shown, with no exceptions including four different frothers, higher frother concentration is in the bulk than in the froth. The results also show strong partitioning giving an increase in bubble size which implies there is a compelling relationship between these two, represented by C Froth/C Bulk and D 32. The C Froth/C Bulk and D 32 curves show similar exponential decay relationships as a function of added frother in the system, strongly suggesting that the frother concentration gradient between the bulk solution and the bubble interface is the driving force contributing to bubble size reduction. © 2014 Central South University Press and Springer-Verlag Berlin Heidelberg.


Zhang W.,Chinalco China Copper Corporation Ltd | Zhang W.,McGill University | Finch J.A.,McGill University
Journal of Central South University | Year: 2014

Froth flotation is a widely used process of particle separation exploiting differences in surface properties. It is important to point out that overall flotation performance (grade and recovery) is a consequence of the quality and quantity of the solid particles collected from the pulp phase, transported into the froth phase, and surviving as bubble-particle aggregates into the overflow. This work will focus on studying these phenomena and will incorporate the effects of particle hydrophobicities in the 3-phase system. Solids are classed as either hydrophilic non-sulphide gangue (e.g. silica, talc), hydrophilic sulphide (e.g. pyrite), or hydrophobic sulphide (e.g. sphalerite). Talc is a surface-active species of gangue that has been shown to behave differently from silica (frother adsorbs on the surface of talc particles). Both are common components of ores and will be studied in detail. The focus of this work is to investigate the role of solids on pulp hydrodynamics, froth bubble coalescence intensity, water overflow rate with solids present, and in particular, the interactions between solids, frother and gas on the gas dispersion parameters. The results show that in the pulp zone there is no effect of solids on bubble size and gas holdup; in the froth zone, although hydrophilic particles solely do not effect on the water overflow rate, hydrophobic particles produce higher intensity of rates on water overflow and bubble coalescence, and many be attributed to the water reattachment. © 2014 Central South University Press and Springer-Verlag Berlin Heidelberg.


Zhang W.,Chinalco China Copper Corporation Ltd | Zhang W.,McGill University | Nesset J.E.,McGill University | Finch J.A.,McGill University
Journal of Central South University | Year: 2014

The specific results of the work investigating the effect of gas density and water temperature on bubble size were present. These were surrogate variables designed to investigate the effect of viscosity (varying water temperature) and altitude (varying gas density). The results show that there is a measurable but relatively small effect of gas density on bubble size. The D 32 is revealed to increase proportionally as (ρ 0/ρ g)0.132. The projected impact on flotation kinetics at 4500 m versus sea level is small, of the order of 0.5% recovery loss for a bank of eight flotation cells. The effect of water temperature (4-40 C) on bubble size is more significant than gas density. The relationship correlates with water viscosity values quite closely. A finding that D 32 increases proportionally as (μ/μ20) 0.776 highlights the importance of accounting for viscosity effects if, for example, large process temperature fluctuations or deviation from design/test conditions are expected. © 2014 Central South University Press and Springer-Verlag Berlin Heidelberg.


Zhang W.,Chinalco China Copper Corporation Ltd | Zhang W.,McGill University | Nesset J.E.,McGill University | Finch J.A.,McGill University
Journal of Central South University | Year: 2014

This work aims to provide a relationship of how the key operational variables of frother type and impeller speed affect the size of bubble (D 32). The study was performed using pilot-scale equipment (0.8 m 3) that is up to two orders of magnitude larger than equipment used for studies performed to date by others, and incorporated the key process variables of frother type and impeller speed. The results show that each frother family exhibits a unique CCC95-HLB relationship dependent on n (number of C-atoms in alkyl group) and m (number of propylene oxide group). Empirical models were developed to predict CCC95 from HLB associated with other two parameters α and β. The impeller speed-bubble size tests show that D 32 is unaffected by increased impeller tip speed across the range of 4.6 to 9.2 m/s (representing the industrial operating range), although D 32 starts to increase below 4.6 m/s. The finding is valid for both coalescing and non-coalescing conditions. The results suggest that the bubble size and bubble size distribution (BSD) being created do not change with increasing impeller speed in the quiescent zone of the flotation. © 2014 Central South University Press and Springer-Verlag Berlin Heidelberg.


Zhang W.,Chinalco China Copper Corporation Ltd | Zhang W.,McGill University | Nesset J.E.,McGill University | Finch J.A.,McGill University
Journal of Central South University | Year: 2014

Effect of frothers in preventing bubble coalescence during flotation of minerals has long been investigated. To evaluate the performance of a frother, an apparatus to measure the bubble size is a basic necessity. McGill Bubble Size Analyzer (MBSA) or bubble viewer that has been developed and completed by McGill University's Mineral Processing Group during the last decade is a unique instrument to serve this purpose. Two parameters which are thought to influence the bubble size measurements by McGill bubble viewer include water quality and frother concentration in the chamber. Results show that there is no difference in Sauter mean (D 32) when tap or de-ionized water was used instead of process water. However, the frother concentration, in this research DowFroth 250 (DF250), inside the chamber exhibited a pronounced effect on bubble size. Frother concentration below a certain point can not prevent coalescence inside the chamber and therefore caution must be taken in plant applications. It was also noted that the frother concentration which has been so far practiced in plant measurements (CCC75-CCC95) is high enough to prevent coalescence with the bubble viewer. © 2014 Central South University Press and Springer-Verlag Berlin Heidelberg.


Finch J.A.,McGill University | Zhang W.,Chinalco China Copper Corporation Ltd
Minerals Engineering | Year: 2014

Although the number and diversity of commercial frothers has steadily increased to meet flotation industry demands, frother selection is still mainly empirical. As part of a general structure-property study, the paper presents a correlation between the critical coalescence concentration (CCC95) and H-ratio for surfactants used as flotation frothers. The CCC95 were determined in 0.8 m3 mechanical flotation cell. The H-ratio was a substitution of hydrophile-lipophile balance (HLB) and determined through high resolution proton nuclear magnetic resonance (1H NMR) spectrometry. A large data set, consisting of 45 surfactants from four frother families, was used to develop the correlation. It is shown that the H-ratio can substitute for HLB. The potential of NMR both to identify the frother family and to derive the H-ratio in predicting CCC95 for commercial frothers is discussed. © 2014 Elsevier Ltd. All rights reserved.


Liu H.-J.,University of Science and Technology Beijing | Liu H.-J.,Chinalco China Copper Corporation Ltd | Zhang W.,Chinalco China Copper Corporation Ltd | Sun C.-B.,University of Science and Technology Beijing
Journal of Central South University | Year: 2014

The performance of a flotation circuit is largely the result of the operator’s response to visual clues. This includes manipulation of the gas input and how it is distributed to cells in a bank. A new gas dispersion technology was presented which was conducted to perform characterization tests in Outokumpu 30 m3 and 50 m3 flotation cells installed at Thompson Vale’s concentrator, and subsequent data analysis. The experimental program was designed to establish “as-found” baseline conditions for each cell of the two-parallel banks in the scavenger-cleaner and recleaner circuit, to select and characterize one typical cell in the two banks with either different frother concentrations or different air flow rates, and establish what variables can be manipulated in future characterization work. A three-parameter model was developed in order to link the bubble size and frother concentration. This relationship can be used to correlate gas dispersion change to improved metallurgical performance. © 2014, Central South University Press and Springer-Verlag Berlin Heidelberg.


Hong-Jun,University of Science and Technology Beijing | Hong-Jun,Chinalco China Copper Corporation Ltd | Sun L.C.-B.,University of Science and Technology Beijing | Xu T.,Chinalco China Copper Corporation Ltd | Zhang W.,Chinalco China Copper Corporation Ltd
IMPC 2014 - 27th International Mineral Processing Congress | Year: 2014

SABC circuits have gained widespread attention within China, and are being gradually applied to many mines. However, the domestic knowledge of comminution process is still relatively basic, and the design and production management of the application of SABC technology lack guidance of scientific theories. This research project focuses on the Phase I SABC milling circuits of Wu Shan Porphyry copper mine. Targeting the design and operation problems of existing process and circuit, and without increased investment and alterations in equipment, the new technologies will combine ordinary crushing and grinding theories as theoretical guidance, and borrow JK Simulation Software (JKSimMet) for analysis in order to optimize the comminution process, efficiently allocate production output and energy consumption, eventually resulting in increased production and energy efficiency. Using JKSimMet Simulation Software, and combining theoretical optimizing and practical production techniques, as well as the on-site situation, the eventual SABC comminution process and circuit optimization plan is: increasing the grinding Ball charge from 8% to 10% v/v in the SAG mill; Setting the Ball charge in the Ball mill to 27% v/v and the maximum operating power draw to 5 800kW; replacing the HP Series crusher with a TRIO TC84 crusher, which is without a power controller, and adding a pebble bin. The final optimization result is: Maximum system processing capacity increased between 20%-26.7%, specific energy consumption reduced by more 2.0 kWh/t, creating an economic benefit of over 300 million RMB, thus achieving the goal of increased production, reduced energy consumption, and improved profitability.

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