The influence of solvent and demulsifier additions on nascent froth formation during flotation recovery of Bitumen from Athabasca oil sands

In the commercial slurry conditioning and flotation process applied to Athabasca oil sands the primary bituminous froth can contain significant amounts of emulsified water and suspended solids. Previous work [Fuel Process. Technol. 56 (1998) 243] has shown that a small chemical addition during the nascent froth process can yield froth of higher quality, without sacrificing bitumen recovery or increasing tight emulsion-forming tendency. In the present work we have investigated the addition of demulsifiers, mostly water-in-oil (W/O) emulsion breaking agents, in an attempt to encourage water droplet coalescence and separation from nascent froth. It was found that certain combinations of high HLB surfactants and solvents can be added in small amounts during the nascent froth process to cause significant reductions in froth water content without sacrificing bitumen recovery. The existence of an optimum surfactant concentration for such beneficial additives correlates with a minimum in interfacial tension and is consistent with conventional oilfield demulsifier experience. The application of our results could lead to a substantial increase in the throughput capacity of froth handling and treatment plants.     

Identification of abnormal conditions for gold flotation process based on multivariate information fusion and double-channel convolutional neural network

Accurate and in-time working condition identification plays a great role in industrial processes. However, most of the current flotation process identification models only use the characteristics of flotation froth as an identification basis, which often causes identification errors due to the instability of the froth, and a large amount of process data is not fully utilized. In this paper, an abnormal condition identification method based on multivariate information fusion and double-channel convolutional neural network (double-channel CNN) is proposed to achieve higher accuracy. First, a double-channel CNN is used to extract depth features from different distributions of froth images and process data in parallel. Then, double normalized attention mechanism (double normalized AM) and multivariate information fusion methods are used to attach weights to the features and fuse them so as to ensure a higher response of key features and increase the reliability of the identification model. The method shows better performance than existing methods in offline simulations and has been validated online at a mineral processing plant in Shandong.     

Solids motion in flowing froths

Flotation is a widely used process within the minerals processing industry, as well as being used for water treatment and de-inking of recycled paper. The froth phase and its role in the separation achieved is as yet ill understood. A fundamentally based model of the behaviour of solids within a flowing froth allows for a fuller understanding of the froth phase of flotation vessels and process optimisation.This paper outlines a model for the motion of solids within a flowing froth. It builds on earlier work on the modelling of bubble and liquid motion within a flowing froth and includes all the effects of same phenomena that effect liquid motion, as well as including the effect of solids concentrations on liquid motion.The solids are divided into two classes for the purposes of modelling, namely the attached material, which follows the bubbles, and the unattached material, which mainly follows the liquid, but can move relative to the water by means of hindered settling and geometric and Plateau border dispersion. The attached material consists of hydrophobic particles, while the unattached material can consist of both hydrophobic and hydrophilic particles. Attached particles can become unattached due to coalescence or bursting.Results from simulations are shown to illustrate the movement and concentration of the solids from the pulp-froth interface to the upper, bursting surface and overflowing the weir.     

含油废水气浮处理药剂的应用与研究进展

综述了国内外石油和石化行业含油污水气浮处理药剂的作用机理,种类以及使用性能的近期研究与应用进展,与无机浮选药剂相经,级机浮选药剂具有产生的浮渣量少,效率高等优点,其研究,开发与应用在我国还应得到进一步重视,一些阳离子型共聚物单体的规模化生产问题还有待解决,未来水处理浮选药剂应向多功能,高效,广谱方向发展。     

DTCWT-based zinc fast roughing working condition identification

The surface texture of mineral flotation froth is well acknowledged as an important index of the flotation process. The surface texture feature closely relates to the flotation working conditions and hence can be used as a visual indicator for the zinc fast roughing working condition. A novel working condition identification method based on the dual-tree complex wavelet transform (DTCWT) is proposed for process monitoring of zinc fast roughing. Three-level DTCWT is implemented to decompose the froth image into different directions and resolutions in advance, and then the energy parameter of each sub-image is extracted as the froth texture feature. Then, an improved random forest integrated classification (iRFIC) with 10-fold cross-validation model is introduced as the classifier to identify the roughing working condition, which effectively improves the shortcomings of the single model and overcomes the characteristic redundancy but achieves higher generalization performance. Extensive experiments have verified the effectiveness of the proposed method.     

Application of Image Processing and Adaptive Neuro-fuzzy System for Estimation of the Metallurgical Parameters of a Flotation Process

It is a well-known fact in the literature and practice that flotation froth features are closely related to process conditions and performance. The authors have already developed some reliable algorithms for measurement of the froth surface visual parameters such as bubble size distribution, froth color, velocity and stability. Furthermore, the metallurgical parameters of a laboratory flotation cell were successfully predicted from the extracted froth features.

In this research study, the fuzzy c-mean clustering technique is utilized to classify the froth images (collected under different process conditions) based on the extracted visual characteristics. The classification of the images is actually necessary to determine the ideal froth structure and the target set-points for a machine vision control system. The results show that the captured froth images are well-classified into five categorizes on the basis of the extracted features. The correlation between the visual properties of froth (in different classes) and the metallurgical parameters is discussed and modeled by the adaptive neuro-fuzzy inference system (ANFIS). The promising results illustrate that the performance of the existing batch flotation system can be satisfactorily estimated from the measured froth characteristics. Therefore, the outputs from the current machine vision system can be inputted to a process control system.     

Diesel Oil Removal by Froth Flotation Under Low Interfacial Tension Conditions II: Continuous Mode of Operation

Abstract

The objective of this study was to investigate the relationship between interfacial tension (IFT) and foam characteristics and the efficiency of diesel oil removal from water in a continuous froth flotation column. The effects of operational parameters, including surfactant concentration, salinity, oil-to-water ratio, foam height, air flow rate, and hydraulic retention time (HRT) on the oil removal were investigated in the continuous mode of a froth flotation operation and compared to batch operation results. Unlike the batch system, for the continuous system used in the present study, having only branched alcohol propoxylate sulfate sodium salt surfactant (C_14–15(PO)₅SO₄Na) and NaCl present in the solution yielded such poor foam characteristics that a stable froth which overflowed the flotation column could not be produced, so the addition of sodium dodecyl sulfate (SDS) as a froth promoter was used to improve the foam stability. Unlike the batch froth flotation system with only C_14–15(PO)₅SO₄Na, the continuous froth flotation with the mixture of C_14–15(PO)₅SO₄Na and SDS, it was not possible to find a SDS and a NaCl concentration at which both ultralow IFT and good foaming were both achieved. Foam formation, stability, and production rate were found to be crucial parameters to the froth flotation efficiency. The continuous froth flotation system offers a high diesel oil removal of 96% in the single stage unit. Demonstration of efficient operation in the continuous mode in this work is important to the practical application of froth flotation in large scale processing.     

Effect of Temperature on the Stability of Froth Formed in the Recycle Process Water of Oil Sands Extraction

The formation of a stable froth on the top of separation vessels plays an important role in bitumen flotation during bitumen recovery from oil sands. The effect of temperature on the stability of froth using recycle process water employed in bitumen extraction was investigated using a water column. The froth became less stable with increasing solution temperature. Once the solution temperature increased above 50°C, irreversible precipitation of the surfactants present in the recycle process water was observed, resulting in a less stable froth.     

CHARACTERIZATION OF FLOTATION PROCESSES WITH SELF-ORGANIZING NEURAL NETS

Flotation processes are difficult to describe fundamentally, owing to the stochastic nature of the froth structures and the ill-defined chemorheology of the froth. Considerable information on the process is reflected by the structure of the froth. In previous work it has been shown that structural features extracted from flotation froths can be related to the behavior of flotation processes in a qualitative way through the identification of certain behavioral regimes or classes by using a supervised neural net as classifier. Although useful as an aid to control decisions, this method is less suitable for quantitative or dynamic analysis of the behavior of flotation plants. In this paper a new method for the analysis of flotation plants is consequently proposed, based on the use of order preserving maps of features extracted from digitized images of the froth phase. The construction of these maps by means of a self-organizing neural net is demonstrated by way of examples concerning the analysis of industrial copper and platinum flotation plants.     

Modeling the Relationship between Froth Bubble Size and Flotation Performance Using Image Analysis and Neural Networks

Machine vision technology now offers a viable means of monitoring and control of froth flotation systems. In this study the relationship between process conditions and the surface bubble size as well as the process performance in the batch flotation of a copper sulfide ore is discussed and modeled by neural networks. Flotation experiments are conducted at a wide range of process conditions (i.e., gas flow rate, slurry solids %, frother/collector dosage, and pH) and the froth mean bubble size along with the metallurgical parameters are determined for each run. An adaptive marker based watershed algorithm is successfully developed for segmentation of the froth images and measurement of the bubble size at different conditions. The results show that there is a strong correlation between process conditions and the froth mean bubble size, which is of great importance for control purposes. Even though the metallurgical parameters can be estimated from the froth mean bubble size alone, other froth features (i.e., froth velocity, color, and stability) are required to be measured in order to achieve more accurate predictions of the process performance.     

Diesel Oil Removal by Froth Flotation Under Low Interfacial Tension Conditions I: Foam Characteristics,and Equilibration Time

Abstract

Froth flotation is a surfactant‐based separation process which is suitable for treating dilute wastewaters. To achieve high performance for the froth flotation operation, the combination of an ultra‐low interfacial tension (IFT) between excess oil and excess water phases, high foam production rates, and high stability of the foam produced, must be attained. To obtain the ultra‐low interfacial tensions, a Winsor Type III or middle phase microemulsion has to be formed. In this study, branched alcohol propoxylate sulfate sodium salt with 14–15 carbon number and 4 PO groups (Alfoterra 145–4PO) was used to form microemulsions with diesel oil. From the results of this work, an increase in surfactant concentration decreased the IFT, and increased foam stability. To obtain the minimum IFT in the region of a Winsor Type III microemulsion, the addition of 5 wt.% NaCl was needed. However, this optimum salinity does not result in effective froth flotation due to poor foam characteristics. The results indicate that both the IFT and the foam characteristics should be optimized to achieve high efficiency of oil removal in a froth flotation operation. Unlike the previously‐studied ethylbenzene system, agitation of the solution before introduction into the flotation column yielded the lowest diesel oil removal efficiency because of the poor foam characteristics compared to either unagitated systems or systems allowed to equilibrate for one month.     

Distribution of clay minerals in the process streams produced by the extraction of bitumen from Athabasca oil sands

This study investigates the affinity of clay minerals in oil sands for the water‐continuous tailings and hydrocarbon‐continuous froth streams produced from the extraction of bitumen from oil sands. Clay minerals in oil sands processing impact bitumen flotation in separation vessels, emulsion formation during froth treatment, and fine tailings behaviour. X‐ray diffraction of oriented clay slides and random powder samples were used to quantify the clay minerals in the oil sands ore and process streams. Particle size distribution and clay activity balances were also conducted around the extraction process. The degree of partitioning during the conditioning and flotation stages in a batch extractor was determined by the surface properties of the clay minerals present. The water‐continuous tailings stream was further separated into fine and coarse tailings fractions through sedimentation. The bulk of the clay minerals reported to the fine tailings stream. Illite and mixed layered illite‐smectite partitioned less to the hydrocarbon‐continuous froth than kaolinite. Also, the illite‐smectite in the froth stream appeared to be different from the illite‐smectite in the water continuous streams.     

Fluid Flow and Kinetic Modelling in Flotation Related Processes: Columns and Mechanically Agitated Cells—A Review

In this paper, fluid flow and kinetic models related to minerals flotation process are presented and the advantages and limitations of using this type of models are discussed. The modelling of such processes was firstly developed assuming perfect mixing for the whole system as a black box. Then, a more realistic approach was developed recognizing the interaction between two zones, the particle–bubble collection zone and the froth transport zone.

From a hydrodynamic point of view, experimental data showed that single large mechanical flotation cells can deviate significantly from perfect mixing, while the mixing conditions in a flotation bank of mechanical cells (three to nine cells in series) can be well described as a series of continuous perfectly mixed reactors. From plant experience, it was observed that performance of large industrial pneumatic flotation columns, originally regarded as a counter-current operation, also operate closer to a single perfectly mixed reactor.

Advances in the field of modelling and design of flotation cells and columns, have been achieved because the fluid flow regime, the mass transport conditions at the pulp/froth interface and the froth transport mechanisms are better known and understood. Key parameters such as the bubble surface area flux, related to the bubble generation and the rate of particle collection, bubble loading related to the mass transport across the pulp-froth interface and froth recovery, which is mainly related to the gas residence time in the froth, are relevant for a deeper understanding of this type of equipment.     

修井返排液快速处理技术优化研究

气浮除油技术因其工艺成熟、效果显著、成本低廉、操作工艺简单、处理量大等优点而广泛应用于含油污水的处理。文章针对胜利油田修井返排液的不同现场情况,开展了气浮除油及精过滤技术的研究,通过实验研究,优选出了最佳的化学药剂;优化了气浮工艺参数和精过滤工艺参数。制定了一套完整的、现场适用性强的工艺技术方案,有效地指导了现场的施工应用。     

Optimization of some parameters in column flotation and a comparison of conventional cell and column cell in terms of flotation performance

In this study, a comparative evaluation was made between column and mechanical flotation cells for fine coal cleaning. In addition, the optimum values of operating parameters were examined, which are important to achieve a desired separation performance in column flotation, such as the frother concentration, the collector dosage, the froth thickness, the wash water rate, the air rate and the feeding rate. The coal sample was collected from a classifying cyclone overflow stream consisting of nominally −130 μm material. Ash, volatile mater, fixed carbon and total sulfur contents of the sample were found to be 47.50%, 20.80%, 31.70% and 0.75%, respectively. Comparison of the column and mechanical flotation results indicated that column flotation was considerably more efficient than mechanical flotation for fine coal cleaning. High froth thickness and wash water addition during column flotation made it possible to obtain cleaner coals. The column flotation produced a 15.60% product ash with a 50.92% clean coal yield and 81.85% combustible recovery.     

Froth Flotation of Mineral Particles: Mechanism

This work provides a review on literature works that investigated the mechanisms controlling particle-bubble interactions in the froth flotation process. The three-zone model comprising collision step, attachment step, and detachment step was discussed in detail. Theoretical and experimental studies were summarized.     

Improvement of the Flotation Selectivity in a Mechanical Flotation Cell by Ultrasound

In this study, the effect of ultrasound on froth and pulp phases has been investigated in the flotation of two different ore samples, namely barite and chalcopyrite. In order to determine the overall flotation rate constants at various froth depths, incremental recoveries obtained from the flotation tests with and without ultrasound were fitted to a first-order rate equation. Thus, the recoveries of froth and pulp phases were calculated.

The use of ultrasound speeded up the bubble coalescence and therefore reduced the froth phase recovery in the ultrasonic flotation of both barite and chalcopyrite. In addition, the results indicate that there is a considerable effect of ultrasound on the pulp phase recovery in the chalcopyrite flotation whereas no significant differences in the separation performance were obtained from the ultrasonic flotation of barite with and without ultrasound. The results also indicate that a pronounced selectivity effect was obtained from the ultrasonic flotation of both barite and chalcopyrite. The use of ultrasound in the froth remarkably improves the quality of the chalcopyrite concentrate, especially at the shallow froths. Therefore, either effective pulp volume can be increased without sacrificing the separation selectivity or the pulp density can be decreased to obtain better product quality at shallow froths in the ultrasonic flotation of chalcopyrite.     

Development of a vision‐based online soft sensor for oil sands flotation using support vector regression and its application in the dynamic monitoring of bitumen extraction

Extraction from oil sands is a crucial step in the industrial recovery of bitumen. It is challenging to obtain online measurements of process outputs such as bitumen grade and recovery. Online measurements are a prerequisite for innovating better process control solutions for process efficiency and cost reduction. We have developed a soft sensor to provide online measurements of bitumen grade and recovery in a flotation‐based oil sand extraction process. Continuous froth images were captured using a VisioFroth camera system on a batch flotation unit. A support vector regression (SVR) model with a Gaussian kernel was constructed to develop a soft sensor for bitumen grade and recovery using froth image features as the inputs. The model was trained and validated for batch flotation of different grades of oil sands ore at industry‐relevant process conditions. A Dean‐Stark analyzer was used to obtain offline grade and recovery measurements that were used to calibrate the soft sensor. Mean squared errors (MSE) of 62 and 74 were achieved for grade (%) and recovery (%), respectively, and this was obtained using 5‐fold cross validation. The developed soft sensor model has been applied successfully in the real‐time dynamic monitoring of flotation grade and recovery for different grades of ore and operating conditions.

     

大处理量紧凑型气浮装置的数值模拟

目前鲜有关于大处理量气浮装置结构设计研究方面的报道,气浮装置国产化研究进程缓慢。为了解决这 一问题,本文以自主研发的处理量为120m³/h 紧凑型气浮装置为计算模型,采用Eulerian 模型和RNG k-ε 湍流模 型,运用Fluent 对其三维流场进行了数值模拟研究。分别研究了内筒高度、半径间隙及入口管径等结构参数和 含油量、处理量等操作参数的影响,以便考察和优化气浮装置的分离性能。结构参数影响的数值模拟结果表明: 随着半径间隙的减小,除油率先增大后减小;随着入口管径的减小,除油率先减小后增大;改变内筒高度对除 油率的影响较小。操作参数影响的数值模拟结果表明,装置的操作弹性相对较大,对水质水量一定程度的波动 具有良好的适应性。