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By Bertil I. Pålsson, Sture V. Persson, Kent T. Tano

"Grinding is one of the most energy consuming unit operations and is also a very inefficient and costly process. Therefore, it is of great importance to run the grinding process as efficiently as possible. The most common way today to control grinding processes is by measuring the power draw of the mill and try to keep it at a maximum level. However, some studies (Kawatra, 1989, Koivistoinen, 1989, Moys, 1989) have shown that this measurement doesn.t reflect everything that takes place inside a mill. Among other parameters like slurry rheology, temperature and charge behaviour, the volumetric filling of a grinding mill seems to have a large influence on the grinding efficiency (Herbst, 1988, Koivistoinen, 1992, Vermeulen, 1988). A problem in attempting to measure those parameters has been to get a sensor that is both robust and sensitive enough for continuous on-line measurement.This paper presents a method for the measurement of the apparent filling level in a pilot ball mill equipped with the Metso Continuous Charge Measurement system (CCM). In this technique a strain gauge sensor is mounted on a flat steel spring which is fitted into a recess underneath a lifter bar. In addition, a conductivity probe, the Boliden Grinding Measurement System (GMS), is mounted in another lifter bar with the purpose of comparing the two measurements. To visualise the behaviour of the charge a DEM modelling technique is used.The results indicate that the system is capable of following the normal variation that occurs in the mill. The signal also very well reflect changes in operating variables such as ball charge level, pulp density and rotational speed. By studying the nature and different features of the signal one can get a better understanding of milling circuit dynamics. Another feature of the technique is the possibility for an operator to continuously follow the grinding process and thereby run the process under optimal conditions."

Jan 1, 2003

By Liu Chun-Bao Sun, Hong-Jun, Wei Zhang, Tao Xu

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.

Jan 1, 2014

By A. A. Remes

High precision on-line particle size distribution measurement of mineral slurries has recently be-come available. It provides new tools for the development of monitoring and optimization methods for mineral grinding and separation circuits. The paper presents the development work at the Kemi chromite concentrator plant of Outokumpu Tornio Works in Northern Finland. The Kemi concentrator processes annually 1.2 Mt of chromium ore. The products are upgraded lumpy ore and metallurgical grade concentrate. The concentrate is produced using gravity separation methods, preceded by a rod mill - ball mill grinding stage. The separation process performance is strongly dependent on the particle size distribution of the grinding product at the Kemi plant. Particle size distribution has a significant effect on the concentrate grade and recovery. Currently a new laser diffraction based on-line particle size analyser is used for monitoring the grinding product. The analyser system allows the measurement of the whole cumulative particle size distribution simultaneously. It provides a wealth of new measurement information for process control. A monitoring and optimization scheme for grinding and gravity separation based on the particle size information is presented. The goal is to minimize the production of fine slime, and subsequently to improve the concentrate quality and minimize chromite recovery losses. Data-based recursively identified linear PLS process models are developed for optimization purposes. The preliminary results of the monitoring system operation in on-line use are presented.

Jan 1, 2014

By G. Y. He

The large-scale 8.53m×3.96m (28?×13? F/F) SAG mills was first applied in Donggua Hill Copper Mine which processes 13,000 tons ore per day. The crushing and grinding circuit went into operation in the Donggua Hill plant in October 2004. However, at the beginning, the productivity of grinding only reached 58% of the capacity expected and some indexes of the crushing and milling circuit didn?t meet the requirements. Especially, the total load of the 8.53m×3.96m (28?×13? F/F) SAG mills was up to 34%~41% (25%~30% designed)and some hard rocks with the size of 25~70mm, which can?t be treated as a medium or even would be crushed and make larger ores or steal balls necessary, were seriously accumulated in the SAG mills. Consequently, they occupied the effective mill volume which in turn reduced the efficiency of the SAG mills and increase the energy consumption. In order to solve the problem of accumulation in the SAG mill and increase its productivity, some measures were taken, such as passing more hard pebble through the grate at mill dis-charging end, changing the type of steal balls and so on. And the results showed that these measures functioned well and had good effects, which is that the filling percentage of the SAG mills has been reduced to 26%~29% from 34%~41% with the composition of particle sizes improved a lot and the productivity increased by 77.4% reaching up to 13,380 tons per day.

Jan 1, 2014

By A. K. Majumder

In an effort to test the extent to which fundamental fluid mechanics can provide a prediction of particle separation, a study on a simple parallel-sided sluice has been carried out using glass bead and ilmenite mixtures at various particle concentrations and flow rates. Great care was taken to devise a flow splitter at the end of the sluice that permitted accurate measurement of the fluid flow profile and collection of slurry samples, allowing evaluation of the particle species concentration profiles. The actual particle separation taking place was compared to predictions made by first describing the fluid flow by a modified ?law of the wall? model. The hydrostatic pressure variation in the flow was taken into account and the eddy viscosity was calculated from a mixing length expression incorporating Van Driest?s damping function. Using an average density and viscosity provides an explicit expression for the velocity gradient that can be numerically integrated for the flow profile. The particle concentration distributions were then modelled with Hunt?s sediment transport model assuming the particle eddy diffusion coefficient to be the same as that for the water. Hindered settling velocities of the particles were calculated using Brauer and Thiele?s formula, which takes the particle size and density distributions and solids volumetric concentration into account. The resulting predictions of particle separation are shown to be a strong function of the settling velocities of the particles used. Keywords: flowing film concentrators, fluid velocity

Sep 1, 2012

By M. K. Aydogan

Today, arsenic has become a much greater problem than before because of the limitations introduced by WHO and USEPA that are lowered from 0.05 ppm to 0.01 ppm. In the nature Arsenic is mostly found as inorganic compounds in the forms of arsenite (As+3) and arsenate (As+5) in aqueous solutions. Arsenic contamination in ground and surface waters has been encountered in almost every country. This element has a carcinogenic effect and can occur in natural sources and anthropogenic sources such as metal mining, groundwater usage and industrial activities. In this study adsorbing colloid flotation was applied in the presence of aluminum sulfates. In the experiments SDS and K-Oleate were used as collectors while MIBC was the frother employed. The effects of collectors and aluminum/arsenic ratios on the removal of arsenic were examined under various pH values. It was found that arsenic removal enhanced with increasing aluminum concentration. Furthermore, it was observed that pH was a very critical parameter in all experiments. The best results were obtained when initial As: SDS: Al concentrations were 10:40:40 ppm at pH 5.5. At this concentration, the efficiency of arsenic removal found to be 99.9%. Keywords: arsenic, adsorbing colloid flotation, aluminum sulfate

Sep 1, 2012

By I. S. M. K. Ilankoon

In heap leaching the transport of the acid from the drippers to the surface of the ore particles is a major factor in the overall performance of a heap. This flow behavior is complex as the flow is unsaturated and occurs along a tortuous set of inter-particle channels and connections. Previous modeling of this system has used equations from oil and ground water flow to model these systems, but the applicability of these models with the larger particles found in typical heaps is suspect as these systems are not necessarily capillary dominated. In particular, as the characteristic particle size goes from below to above a few centimeters, the flow changes from capillary to gravity dominated. This means that typical heap leaching heaps cover this interesting, but complex, transitional fluid flow regime. In this paper a set of experimental studies of this flow, including PEPT (positron emission particle tracking) based tracer experiments, highly accurate liquid holdup measurements and axial dispersion experiments using salt tracers will be presented. In this study, flow through mono-dispersed particle beds was carried out. In particular, the hysteresis in the liquid holdup as the liquid flow rate into the particle bed is varied is investigated, since this hysteresis means that the relationship between flow rate and holdup is history dependent, an effect not included in models currently used to describe fluid flow in heaps. A theoretical model that describes this hysteresis will also be presented. Keywords: heap leaching, hydrometallurgy, modeling

Sep 1, 2012

By M. Roy

Coke combustion during sintering process is significantly governed by coke breeze size distribution, which in turn affect sinter quality i.e. sinter granulometry, Tumbler index, Reduction Degradation Index and Reducibility Index of sinter. To know the effect of microfines of coke breeze on sintering process parameters, pot sintering tests were conducted and it was found that when microfines are eliminated and optimum coke size (1-3mm) is used yield of sinter increased by more than 7%. Similarly productivity increased by 9%, the strength of sinter i.e. ISO Tumbler Index increased by 2.3% and +10mm sinter size increased by 5.5%. Controlling of microfines during crushing and by improving crushing index will result in improved quality and productivity of sinter with lesser amount of coke breeze. This paper describes that how to optimize solid fuel i.e. coke breeze consumption in sintering process through granulometry control. Keywords: iron ore sintering, coke breeze granulometry, productivity of sinter, quality of sinter

Sep 1, 2012

By S. K. Sharma, R. Markandeya, G. Venkateswara

"In this study, a three level Box- Behnken factorial design combined with Response surface methodology (RSM) for modeling of process parameters of Multi Gravity Separator (MGS) for recovery Iron values from sub grade iron ore, Deposit No. 5, Bailadila complex has been developed. The three significant operational parameters of MGS, Drum rotational speed (RPM), Drum inclination (degrees) and quantity of wash water (LPM) were considered in the experimental work. Other parameters like feed percent solids, shake frequency and shake amplitude were maintained constant. The ‘as received’ sub grade iron ore sample is admixture of lump and fines and chemically assayed 40.80% Fe, 40.90% SiO2, 0.24% Al2O3 and 0.22% Loss on Ignition (LOI). The obtained results were evaluated with the Box-Behnken factorial design, RSM and also Quadratic programming(QP). Second order response functions were produced for Fe in terms of grade (%) and recovery (%) of the concentrate fraction. Taking advantage of QP, it was observed that maximum grade of 62.21% Fe achieved at an inclination of 4.3degrees, 2.7LPM of wash water and at a drum speed of 198 RPM. Similarly a maximum Fe recovery of 65.37% weight can be achieved at 4.3degrees inclination, 2.6LPM wash water and at a rotational speed of 212 RPM Predicted values of responses obtained using model equations were in good agreement with the experimental values. The influence of the process variables of the multi gravity separator concentrator on grade and recovery of concentrate fraction were presented and discussed."

Jan 1, 2014

By Avishan Atrafi, Marek Pawlik

"Gas dispersion properties of sodium salts of 6, 12 and 18-carbon fatty acids (hexanoic, lauric and oleic acid) were investigated as a function of pH. A strong effect of pH was observed on gas dispersion properties of fatty acids. At high pH for 12 and 18 carbon fatty acids, at which these surfactants formed a true solution, the gas dispersion properties were similar to those of MIBC. In the case of sodium hexanoate, which has a much higher solubility than the longer chain fatty acids and therefore does not form precipitates, the gas dispersion properties of this surfactant were strongly enhanced in the acidic pH range, where hexanoic acid was fully associated. This result is an indication that undissociated hexanoic acid is much more surface-active than anionic hexanoate. Only a small effect of the surfactant chain length on gas dispersion properties of the tested reagents was observed. The measured critical coalescence concentration (CCC95) values increase slightly by decreasing chain length and range from 5.8 x 10-5 mol/L (17.7 mg/L) for sodium oleate to 7.2 x 10-5 mol/L (16 mg/L) for sodium laurate at pH 10 and 1.9 x 10-4 mol/L (26 mg/L) for sodium hexanoate at pH 3.7. These are compared to CCC95 of MIBC, which is measured to be 8 x 10-5 mol/L (8 mg/L). The soluble molecular species were recognized as the most effective species in preventing bubble coalescence."

Jan 1, 2014

By Gabriela Pino, Maurício Torem, Lorgio V. Gonzales

It has been long known that many microorganisms are able to interact with mineral particles to obtain a concentrate; thus, one possible technique is flotation and its related process. Biological process have been attracting attention in mineral processing due to lower operating cost and their possible applications to process low-grade and fine ores. The adhesion of microorganism to surface of mineral particles can alter the hydrophobicity of mineral markedly. Such surface modifications modify its hydrophobicity or hydrophilicity will be used to flotation of cassiterite fines. The major difficult to float fine particles is attributed to the low probability of bubble-particle collision, one characteristic of electroflotation process is the ability to create very tiny bubbles, which is known, improve the collision efficiency and flotation performance of fine particles. In this study, the electroflotation of fine particles using Rhodococcus opacus strain as bioreagent was investigated. Electroflotation experiments were carried out using particles of cassiterite around 8µm of mean diameter the adsorption of R. Opacus onto cassiterite particles was confirmed by Fourier transform infrared spectroscopy (FTIR), electrokinetic and contact angle analyses. The measurement of bubble size by laser diffraction showed a mean bubble size of around 26 µm, current density and bacteria concentration appear to be the main parameters affecting the mean diameter of bubbles, electroflotation tests reported recovery around of 64.5 % at pH 5, concentration of 2,87 x10¹² cells/ml (50 mg/L) and current density of 51,4 mA/cm2.

Jan 1, 2014

By Markus A. Reuter, Bernardete Castro, Antoinette van Schaik, Han Remmerswaal

This paper describes the inseparable relation between product design, liberation, and metallurgical recovery in the optimisation of the recycling of passenger vehicles. This is illustrated by the use of an optimisation model that uses among others a material combination matrix based on metallurgical process data, which depicts the consequences of the quality of intermediate recycling products on the metallurgical material recovery and final alloy metal quality. Various simulations will illustrate the effect of changes in product design and hence liberation on the recycling of end-of-life vehicles. Although this paper focuses on cars, the discussion is equally valid for any end-of-life product. Calibration of the model will be discussed with reference to experiments carried out in order to study the optimal recovery of aluminium applications used in passenger vehicles.

Jan 1, 2003

Much has been published in recent years on the challenges facing the engineer of the 21st century and the consequent challenges facing the education providers and industry. The world is changing rapidly on the social, economic, political, technical and environmental fronts and our metallurgists/mineral processing engineers of the future will arguably need to have a different set of skills than those which were traditionally regarded as adequate during the latter half of the 20th century. This paper attempts to explore some of these issues and their ramifications.

Jan 1, 2014

By Z. L. Huang

A new porous apatite product was prepared using phosphorite from Yichang China by a tem-plate-directed method in self-made reaction equipment under constant temperature and pressure. The product was characterized by XRD, FT-IR and SEM. The results showed that the product was a kind of micrometer porous sphere three-dimensionally structured by apatite nanoflakes, that the average thickness of nanoflakes was about 50 nm, that the average pore size was about 1.2 µm and that the particle average size was about 20 µm. Great amounts of Ca2+channel, high special surface area and regular spherical shape show the potential promising applications of this special porous apatite product in the fields of catalyst, medication, chemical engineering and environment engineering

Jan 1, 2014

By Tamal K. Ghosh

In this study, the QEMSCAN technology is used to acquire quantitative modal, textural, mineral association and liberation data on different products generated from with or without washing, fractionation by size and density using screens and heavy liquids/panning, which has provided significant information on the quality and beneficiability of four categories of low Grade iron ores from Jharkhand-Orissa region. The deposit of low Grade iron ore has been categorized into four categories viz. Grade-I with <45% Fe(t) a) containing shale rich type and b) BHJ rich type; Grade-II with 45-55% Fe(t) and Grade-III with >55% Fe(t) containing conventional flaky, hard, kanga, lateritic, shale and BHJ litho/ore types in varied proportions. Mineralogy is similar across all samples being hematite, martite, goethite, kaolinite and gibbsite. Banded Hematite Jasper has difficult liberation characteristics due to highly compact banded mode of silica mineral occurrence with hematite. In all categories, the grade dilution is by the presence of 1) ?Discrete gangue rich litho types? at lump size and 2) ?Within ore types?. The second type of grade dilution contains coating of gangue phases around the iron ore minerals and different degree of locking of gangue phases within iron ore minerals. Further characterization and beneficiation assessment details are discussed in this paper.

Sep 1, 2012

By V. Panayotov, M. Panayotova

"Wastewater from ores processing is often polluted by molybdate and sulfate (SO42-) ions. Sorption is one of suitable methods for removing those pollutants when presenting in low concentrations. This work reports results on adsorption of sulfate and molybdate ions on metal modified (with barium - Ba and lead - Pb) and organic reagent modified (with Hexadecyl-trimethyl-ammonium bromide - HDTMA) clinoptilolite. Zeolite’s modification with Pb, Ba and HDTMA increases its uptake capacity with respect to Mo(VI) at pH 3, with the uptake capacity decreasing in the order CL-Pb > CL-HDTMA > CL-Ba. Lead-modified clinoptilolite shows high uptake with respect to Mo(VI) in acidic, neutral and slightly alkaline conditions. The presence of SO42- in concentrations twice higher than the amount of Mo(VI) do not interfere with the Mo(VI) removal by CL-Pb. Zeolite’s modification with Ba and Pb renders it able to immobilize SO42- from water in the pH range 3-9. Kinetics of the uptake process is best described by the pseudo-first order kinetic equation. Increasing the initial concentrations of Mo(VI) and SO42- increases the removed amount of pollutants. INTRODUCTION Wastewater from copper-molybdenum ores processing is often polluted by molybdate and sulfate ions. Molybdenum (Mo) migrates easily in water and consequently the Mo polluted areas could extend for hundreds and thousands of meters (Ryzhenko, 2010). Molybdate anion is the only Mo(VI) species in natural water, i.e. at pH > 6.0. Its median freshwater hazardous concentration affecting 5% of the species (HC 5.50%) is 38.2 mg Mo/L (De-Schamphelaere et al., 2010). The marine water chronic toxicity (HC 5.50%) is assessed at 5.74 mg Mo/L (Heijerick et al., 2012). The predicted no-effect concentrations (PNEC) are 12.7 mg Mo/L and 1.92 mg Mo/L correspondingly for freshwater and marine water (Heijerick et al., 2012a). When sulfates present in drinking water in excess of 250 mg/L they cause a cathartic action (especially in children) in the presence of sodium and magnesium, and when the concentration exceeds 600 mg/L, diarrhea. When sulfate-rich effluents are discharged into the environment, they may increase the acidity of water bodies and soils (Guimarães and Leão, 2014). Because of the adverse effects to human health and the environment, limits are set for SO42- concentrations in waters and wastewaters in the range of 250 / 500 mg/L."

Jan 1, 2018

"The Circular Economy (CE) will play an important role in shaping a resource-efficient society. Enabling this transformation from a linear to a CE requires precise quantification of resource efficiency and thus the economic viability of the system. Based on the development of simulation tools of classical minerals processing and process metallurgy, the Outotec (2018) HSC simulation platform could be further developed (gleaning from many academically published works of the author listed below), permitting the simulation of the CE system and to subsequently calculate its resource efficiency. It enables the estimation of a simulation-based Recycling Index (RI) from a product’s Bill of Material (BoM) and Full Material Declaration (FMD). It is a unique methodology for Design for Recycling (DfR) based on minerals engineering linked to a deep understanding of minerals and metallurgical process engineering. A key to this simulation is a detailed understanding of the mineralogy (both geological and designed) of the CE system and its many products, materials and systems, both in a geological mineral and a product-designer-mineral sense. In addition, a detailed understanding and quantification of the thermodynamic properties of the system (both energy and exergy/entropy) is key to understanding its economics and its limitations. With this approach, the actual losses of the CE system are shown and thus highlights the limits of the CE as defined by minerals and metallurgical process engineering principles. INTRODUCTION From the dawn of the industrial era up to today, many of our products have been created according to the principles of a linear economy: we find resources, make a product, and then dispose of it when we are done using it. But in recent years, there has been a growing awareness of the need to move to a Circular Economy (CE), an approach that aims to maximize the usefulness of products, components and materials across the entire lifecycle. In terms of recycling, this means achieving maximum recovery of materials once products reach the end of their usable life while also maximizing resource efficiency. Of importance is therefore also not only the recovery of critical technology elements that make the CE system run, but also the criticality of the metallurgical infrastructure that must be present to recover these elements economically. Ellen Macarthur (2017) defines the CE as “Looking beyond the current ""take, make and dispose” extractive industrial model, the circular economy is restorative and regenerative by design. Relying on system-wide innovation, it aims to redefine products and services to design waste out, while minimising negative impacts. Underpinned by a transition to renewable energy sources, the circular model builds economic, natural and social capital.” However, when translating this significant message to images, it is striking that the key extractive industry is not depicted in the Ellen Macarthur as well as EU depiction of a CE (EU 2015). Other CE discussions are also wanting in their fundamental detail and description e.g. Accenture (2015) and Beaulieu et al. (2016)."

Jan 1, 2018

By G. Bulut, Ü. Yenial

"Heavy metals contamination in aqueous systems can be found in a variety of industries, in particularly mining, metal processing, finishing and plating. Water containing more than 0.5 ppm heavy metal considered as a toxic due to harmful effects on health. The major techniques employed for heavy metal removal from industrial wastewaters include precipitation, reduction, ion-exchange, and adsorption. Adsorption is a heavy metal removal method for aqueous systems. As a common adsorbent, activated carbon has been used in treatment but it is ineffective on some elements. Thus, there has been a research for developing highly effective and selective adsorbents. In this study the adsorption of lead and arsenic ions on to coal waste and red mud waste was studied. The experimental parameters were determined as pH, equilibrium time and the initial concentrations, activation by heat treatment and the blend of adsorbents. According to their adsorption capabilities, red mud was found to adsorb lead and arsenic ion with high efficiency but coal waste did not adsorb arsenic ion. However the binary adsorptions of these ions were enhanced the adsorption efficiencies. In addition the blend of coal waste and red mud affected the adsorption efficiency. INTRODUCTION As a result of rapidly developing industry and excessive use of water resources, the need of clean water and wastewater management appear as a problem. Wastewater recycling activities and researches come to the fore for an effective use of wastewater. Recycling of wastewater, which contains heavy metals harmful to the environment and human, is a difficult process. Heavy metals are generally divided into three categories: toxic metals, precious metals, radionuclides. Wastewaters from various industries, containing heavy metals, are the main polluters of water and soil. Although their toxic structures, heavy metals are used extensively in industry as they have technological significance. Usually mining industry, metal industry and industrial organizations produce heavy metal containing wastewaters (Volesky 1990, Ting and Lawson 1991, Bishop 2002)."

Jan 1, 2018

By M. Narasimha

The flow in a hydrocyclone classifier is highly turbulent complex nature of multi-phase structure, which has led designers to rely on empirical mathematical models for predicting the performance. A number of classifying cyclone models have been developed and successfully used in mineral comminution circuit simulators over the past four decades (Plitt, 1976 and Nageswararao, 1978). However, most of the mathematical models currently available to describe hydrocyclone classifier performance are based on single average mineral density component behavior. In industrial comminution circuits, the feed to the cyclone composed of a mixture of particles of varying degrees of liberation and sizes. The behavior of multi-component particles in a hydrocyclone is poorly understood and unaccounted for in most of the mathematical model equations available in the literature. There is evidence from a number of experimental data sets indicating the significant influence of the multi-component particles on measured cyclone performance. A concept for modeling the performance of hydrocyclones based on multi-component behavior is proposed in this paper. A set of semi-empirical model equations for cut-size, sharpness of separation are presented and the corresponding model parameters evaluated from the measured data are given.

Sep 1, 2012

By Elisabeth Schmidt

The conventional Canadian oil sand processing, the Clark Rowe process, is associated with many risks for the environment and high energy costs. To recover the bitumen from the oil sand (tar sand), large quantities of water have to be heated up and mixed with caustic soda and the oil sand. During this process, tailings with stabilized clay colloids are formed and dumped in tailings ponds. To avoid these disadvantages, a new, non-aqueous extraction process is to be established. Organic solvents are used instead of water and caustic soda to mobilize the bitumen from the sand-clay mixture. Pressure filtration, washing and steam pressure filtration are part of the new concept. A mixture of organic solvents and the oil sand is first pressure filtrated in a nutsch filter until a saturation level of one is obtained. After the cake has been formed, the filter cake is washed with organic solvent to flush the bitumen loaded solvent out of the cake. The following steam pressure filtration mechanically and thermally removes the remaining volatile components of the solvents from the filter cake. The filtrates from the pressure filtration, the washing phase and partly from steam pressure filtration are subsequently thermally treated to recover the organic solvents and obtain a higher bitumen concentration in the mixture. This mixture is then lead to an upgrader to win synthetic crude oil (SCO). The recovery of bitumen in the conventional hot water extraction process based on the Clark Rowe process can, in highly optimized plants, achieve between 88 and 92 %. Variation of oil sand properties leads to an actual range of between 80 and 90 % of bitumen recovery. With the alternative process based on organic solvents, the bitumen recovery exceeds the recovery of the conventional process by up to 16 percentage points. The composition of the two organic solvents in the first step of forming a suspension with the oil sand is important. The aromatic component is crucial for liberating and solving the asphaltenes, which tend to flocculate. The order of the two components of organic solvents is also important in the washing step. The paraffinic component is essential to achieve successful steam pressure filtration with respect to fast steam breakthrough and a filter cake free from organic compounds, as a result of its lower boiling point. Keywords: oil sand, filtration, organic solvents, pressure filtration, steam pressure filtration, filter cake washing

Sep 1, 2012