Tailings Streams Research Articles

Amplification in the Uncertainty of the Yield and Recovery for a Steady-State Mineral Separator calculated using the Two-Product Formula

This paper presents a simple relationship for estimating the uncertainty in the overall yield and species recovery when the two-product formula is applied to assays of the feed, product and tailings streams of a steady-state mineral separator. The non-linearity of the two-product formula means the reliability of these yield and recovery values can vary significantly. Formal treatment of the problem provides a generalized, albeit complex, expression for the uncertainty (Wills, 1997), limited to relatively small input disturbances. This paper explores the problem further using Monte Carlo simulations, covering the effects of relatively small through to relatively large input disturbances. Assay values for the feed, GF, product, GP, and tailings, GT, were assumed to have the same relative uncertainty. The work focussed on the amplification in the uncertainty of the yield, AY, and recovery, AR, resulting in very simple expressions, AY ∼ 2GF/|GF – GT| and AR ∼ 2GT/|GF – GT|.

Iron ore tailings valorization through separate characterization and upgradation of different tailings streams of an Iranian iron ore processing plant.

In iron ore processing plants, different tailing streams are usually transferred to the tailings thickener for partial dewatering and finally transferred to the tailings dam as a single stream. Therefore, the mixing of different tailings streams happens. This way can challenge the process of reprocessing the tailings in the tailings dam since the mixing of different tailings streams causes more complexity in the mineralogical composition as well as the chemical composition of the tailings in the tailings dam. To solve this problem, the idea of separate characterization and separate upgradation of different tailings streams of an iron ore processing plant was carried out and a comparison was made between the results of magnetic upgradation of each tailings streams with the total tailings (i.e., the tailings in the tailings dam, which is a mixture of different tailings streams of the plant). Hence, the different tailings streams of an iron ore processing plant were sampled and characterize for total iron, FeO content, particle size distribution, mineralogical composition by X-ray diffraction (XRD), magnetic behavior by Davis tube tests, and dry solid tonnage rate. The characterization results showed that the iron grade and dominant iron ore mineral vary from one stream to another tailings stream of the iron ore processing plant. For instance, the total iron content of different tailings streams varies in the range of 18.46 to 64.68% and the dominate iron ore mineral in the Cobber tailings was hematite, but in the other tailings streams it was magnetite. The magnetic upgradation of the Cobber and Rougher tailings and also the total tailings were performed separately by the wet magnetic separation at different magnetic field intensities of 2000, 3500, 5000, and 15,000 Gauss. A concentrate with the highest iron grade of 61.79% and yield of 52.15% was produced from magnetic upgradation of the Rougher tailings, but magnetic upgradation of the total tailings produced a concentrate with the iron grade of 37% and yield of 15.2%. A comparison between the magnetic upgradation of the total tailings and the Cobber and Rougher tailings revealed that the upgradation of Rougher tailings results in a concentrate with higher iron grade and yield than the total tailings.

A study on the recovery of fine chromite from UG2 tailings

The recovery of chromite from the tailings streams of South African UG2 platinum concentrators adds significant financial returns to these operations. Whilst the coarser fractions are amenable to processing by physical separation, the focus is now also on the recovery of fine (typically −75 µm) chromite by flotation.This paper describes the results of a series of physical separation, and chromite bench flotation tests that have been carried out at acidic and natural pH respectively, on UG2 tailings from Pilanesberg Platinum Mines (PPM) on the western limb of the Bushveld Complex in South Africa. The objective of the work is to find a route that would best produce, from a feed assaying around 18 % Cr2O3 and with 50 % of the chromite in the −38 µm fraction, a concentrate of at least 40 % Cr2O3 and an overall yield of more than 13 %.Results showed that shaking tables and wet high intensity magnetic separation (WHIMS) alone were not capable of upgrading the tailings to the target grade. However, flotation tests at a pH of 2.5 on a sample that was deslimed at 10 µm by cycloning, as well as a sample that was screened at 25 µm and subjected to WHIMS, demonstrated that a product assaying 42 % Cr2O3 could be attained at yields between 8 and 11 %, with recoveries ranging between 19 and 27 %. The results highlighted the importance of desliming prior to flotation, in reducing the dosage of the Flotinor V-2711 collector by more than 60 %.Subsequent flotation tests at natural pH on hot tailings samples with two stages of cleaning showed good upgrading, where a feed grade of 16.1 % Cr2O3 after desliming was converted to a concentrate of 29.4 % Cr2O3 at a yield, based on deslimed feed, of 28.6 % and a recovery of 52.4 %. The overall upgrade ratio in this case of 1.83 was slightly lower than those of the acidic tests (i.e., 1.87 and 2.31 respectively) but also at lower yields (28.6 % vs 33 %) and recoveries (52.4 % vs 62 %). Further work is underway to investigate various flowsheet options, including the flotation of fines spiral concentrates, staged collector addition to the cleaning stages, and froth washing.

Investigation of chromite recovery possibilities from coarse and fine plant tailings

Tailing streams of an existing chromite plant were characterized and then beneficiated in different methods. Characterization studies have been indicated that chromite grains finely disseminated on the coarse gangue particles in all size fractions (+100 µm). Increase in fineness did not show a significant effect on disseminated chromite grains during coarse tailing beneficiation studies. Neither a salable concentrate nor an acceptable recovery could not be obtained from coarse tailing. For this reason, optimization studies were focused on fine tailing sample. Removal of the gangue minerals was determined to be more efficient using gravity concentration rather than magnetic separation. The effect of parameters of shaking table were optimized using empirical models. It was determined that grade and recovery in the concentrate majorly depended on the variation of table slope. To achieve high grade (>42%) with acceptable recovery (>40%), a medium level of wash water (>4lpm) and lower level of table slope (

Kuwait to lead the Middle Eastern refinery capacity growth by 2024.

Coal preparation plants are under increasing pressure to reduce their consumption of fresh water leading to the use of recycle water. Recycled water generally contains a large quantity of dissolved inorganic electrolytes, which affect coal flotation. This paper reports the conductivity and pH measurements of water in the tailings stream of an industrial scale flotation cell covering a period of approximately two years. The different coal seams processed at the site were also compared and the influence the water quality on the overall yield of coal assessed. This study presents the large variation in inorganic content in recycled water observed for a wash plant and determines its possible effect on coal preparation. The maximum daily temperature was found to be an important factor controlling the amount of inorganic electrolytes in the water and, very significantly, the water management system implemented. The overall plant performance was somewhat affected by the use of water containing high concentrations of inorganic electrolytes. The effect of the quantity of ions in the water on the flotation process is explored in Part 2.

Bioleaching of cobalt from sulfide mining tailings; a mini-pilot study

Tailings are remaining processing waste streams from mines, disposed after valuable minerals extraction from the mined ore. Tailings contain varying concentrations of residual valuable metals that are currently lost due to lack of economical treatment possibilities. With sulfide containing tailings there is also a risk of acid rock drainage. In this study, iron- and sulfur-oxidizing microorganisms were utilized in bioleaching to treat pyrite-rich tailings to liberate mainly cobalt, alongside with other valuable metals. After adaptation of the microbial culture and batch bioleaching tests, the continuous-batch mode mini-pilot protocol was applied in 10 L stirred tank reactors (30 °C, 100 g/L solid content), reaching high leaching yields for the target metals (Co 87%, Zn 100%, Ni 67%, Cu 43%) in approximately 10 days retention time. The results show potential to turn challenging tailing streams into secondary resource for valuable metals.

Linking hydrocarbon biodegradation to greenhouse gas emissions from oil sands tailings and its impact on tailings management

Microbial research for maintaining soil productivity, health, and environment as well as for ecosystem function has been one of the main research focuses in the Department of Renewable Resources (formerly Department of Soil Science) during the last 100 yr. In recent years, microbial research has been expanded to effectively reclaim disturbed land, remediate contaminated sites, and manage soft sediments such as huge volumes of oil sands tailings. This article highlights the microbial processes in tailings ponds that can affect strategies to manage growing inventory of oil sands tailings and reduce associated environmental footprint. Enormous volumes of fluid fine tailings produced during bitumen extraction from oil sands are retained in tailings ponds. Some tailings streams contain residual labile hydrocarbons originated from the hydrocarbon solvents used in the extraction process. Indigenous microorganisms acclimated to the pond environment metabolize certain fractions of the fugitive labile hydrocarbons into biogenic greenhouse gases (GHG) such as methane (CH4) and carbon dioxide (CO2). Long-term (1–7 yr) biodegradation studies conducted using mature fine tailings (MFT) collected from different tailings ponds reveal that the microorganisms sequentially and preferentially biodegrade hydrocarbons under methanogenic conditions. The stoichiometric mathematical model developed on these biodegradation studies can predict GHG emissions from tailings ponds. Production of biogenic gases also affects the porewater and solid-phase chemistry of MFT and accelerates their de-watering and consolidation during active methanogenesis, which is beneficial for recovery of porewater for reuse in the bitumen extraction process and for effective reclamation of consolidated material.

Constraining the Economic Potential of By-Product Recovery by Using a Geometallurgical Approach: The Example of Rare Earth Element Recovery at Catalão I, Brazil

Abstract Geometallurgy aims to develop and deploy predictive spatial models based on tangible and quantitative resource characteristics that are used to optimize the efficiency of minerals beneficiation and extractive metallurgy operations. While most current applications of geometallurgy are focused on the major commodity to be recovered from a mineral deposit, this contribution delineates the opportunity to use a geometallurgical approach to provide an early assessment of the economic potential of by-product recovery from an ongoing mining operation. As a case study for this methodology, possible rare earth element (REE) recovery as a by-product of Nb production at the Chapadão mine in the Catalão I carbonatite complex is used. Catalão I is part of the Alto Paranaíba igneous province in the Goias Province of Brazil. Currently, niobium is produced in the complex as a by-product of the Chapadão phosphates mine. This production is performed in the Tailings plant, the focus of this study. REEs, albeit present in significant concentrations, are currently not recovered as by-products. Nine samples from different stages of the Nb beneficiation process in the Tailings plant were taken and characterized by mineral liberation analyzer, X-ray powder diffraction, and bulk-rock chemistry. The recovery of REEs in each of the tailing streams was quantified by mass balance. The quantitative mineralogical and microstructural data are used to identify the most suitable approach to recover REEs as a by-product—without placing limitations on niobium production. Monazite, the most common rare earth mineral identified in the feed, occurs as Ce-rich and La-rich varieties that can be easily distinguished by scanning electron microscopy (SEM)-based image analysis. Quartz, Fe-Ti oxides, and several phosphate minerals are the main gangue minerals. The highest rare earth oxide content concentrations (1.75 wt % total rare earth oxides) and the greatest potential for REE processing are reported for the final flotation tailings stream. To place tentative economic constraints on REE recovery from the tailings material, an analogy to the Browns Range deposit in Australia is drawn. Its technical flow sheet was used to estimate the cost for a hypothetical REE production at Chapadão. Parameters derived from SEM-based image analysis were used to model possible monazite recovery and concentrate grades. This exercise illustrates that a marketable REE concentrate could be obtained at Chapadão if the process recovers at least 53% of the particles with no less than 60% of monazite on their surface. Applying capital expenditure and operational expenditure values similar to those of Browns Range suggests that such an operation would be profitable at current REE prices.

R as an environment for data mining of process mineralogy data: A case study of an industrial rougher flotation bank

Through a series of in-house routines of R, an open-source programming language for statistical computing, statistical analysis is applied to automated process mineralogy data to describe the performance of an industrial scheelite rougher flotation bank. These routines allow (1) freeing the user from the limitations of the menu-driven built-in processing and spreadsheet-based analyses routines; in particular when processing data from several streams, and (2) a more flexible manipulation of the data at any level of aggregation.In an illustration case study, it was determined that ideally floating scheelite particles are coarser than 40 µm and are more than 40% liberated. Most of the scheelite lost to the rougher tailings stream is either ultrafine or coarse with little surface liberation and associated with silicates. More importantly, the presence of a depressant does not permit the selective flotation of scheelite from other semi-soluble salt-type minerals such as calcite. This is linked to particle size, as there appears to be some overgrinding before the rougher flotation. While the impact of the depressant requires more observation, less fine grinding could already potentially improve the concentrate grade and decrease operational costs.

Flotation of coarse coal particles in a fluidized bed: The effect of clusters

This paper is concerned with the separation of coarse particles from siliceous gangue, in a fluidized bed froth flotation column, the NovaCell. Coarse particles are allowed to settle in the base of a column, and are fluidized by an upward-flowing stream of liquid. Air bubbles are introduced with the stream, which collide with hydrophobic particles in the bed, carrying them to the top of the vessel as flotation product.The paper describes the use of bubble clusters as a means of recovering particles in a flotation machine. Clusters are buoyant aggregates of bubbles and particles. Copious quantities were observed to form in the fluidized bed, rising to the top of the flotation column. They were present in such volumes that the froth was unable to absorb them all, and a thick cluster layer developed beneath the froth. This layer was drawn off and separated on a screen as a secondary flotation product, in addition to the conventional froth product.Here we describe the flotation of coal particles from different sources with a top size of 2 mm, in a NovaCell fluidized bed contactor. High combustibles recoveries were achieved, at acceptable ash contents, over the whole size range. The froth phase contributed approximately 65% of the total, the balance appearing on the screen. Particles of all sizes from 0 to 2 mm were represented in the froth discharge.The NovaCell gave two flotation products and two tailings streams. It was possible to control the tails from the fluidized bed so that the solids fraction was as high as 60–70%, in the size range 300 µm–2 mm. The results highlight the value of coarse particle froth flotation from a product de-watering perspective, when compared with flotation in conventional cells that are restricted to a top size of 500 µm. The ultrafine fraction less than 74 µm in diameter in the product was reduced by a third when the top size was increased to 2 mm from the normal top size of 500 µm for coal.The fact that low-buoyancy clusters can form beneath the froth, provides an alternative explanation for the phenomenon known as froth dropback.

Determination of clay content in Canadian oil sands using x‐ray florescence spectroscopy for diagnosis of ore processability

AbstractIn this study, a simple and robust method based on the use of x‐ray fluorescence (XRF) spectroscopy to measure potassium content as an indicator of illite in oil sands was proposed and tested. The XRF results of illite determination were compared with those determined using the conventional methylene blue titration (MBT) method. To test the suitability of the XRF method for determining illite content in various streams of oil sands processing as a diagnosis tool, a toluene‐diluted‐bitumen solution was used to contaminate solid surfaces prior to their analysis by the XRF and MBT methods. In order to remove the organic matter from the bitumen‐contaminated solids for evaluating the XRF and MBT method, toluene washing and low temperature ashing were applied to the bitumen‐contaminated solids prior to their analysis. The robustness of the XRF analysis in comparison with the MBT method was further confirmed by analyzing the solids extracted from bitumen froth and tailings stream. The results show that the XRF method was more tolerant to surface contamination and therefore more reliable in determining illite content in oil sands and relevant processing streams. It was also found that the potassium contents measured by the XRF method on solids from 10 ores show a strong correlation with the corresponding fines contents of these ores, indicating that the XRF method can potentially be used to determine the fines content of oil sands and related processing streams.

Rare earth elements in flotation products of coals from East Kootenay coalfields, British Columbia

With the identification of coal deposits that are enriched in rare earth elements (REEs) across the world, coal and coal by-products are considered as an alternative source for REEs due to the combined supply and demand restrictions for these elements. Studies are being conducted to recover these elements from various coal sources. In this study, coal samples from the East Kootenay coalfields in British Columbia, Canada were examined for the presence of REEs in run-of-mine coal samples and flotation products.Results reveal that on an ash basis, the concentration of REEs varies from 174 to 1038 mg/kg in the samples. To understand the REE as sociation, which is essential for extraction purposes, a three-step sequential extraction process along with a mineralogical evaluation using scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDX) and quantitative X-ray diffraction (XRD) data was used. It is found that a significant portion of REEs in the feed samples were reported to middling and tailings streams. The mineralogical analyses reveal REE association with aluminosilicate mineral in the samples.

Simultaneous Extraction of Clean Coal and Rare Earth Elements From Coal Tailings Using Alkali-Acid Leaching Process

With the supply restriction from traditional rare earth deposits, alternative sources of rare earth elements (REEs) such as coal are being studied. The United States National Energy Technology Laboratory has identified US coal deposits as a potential source of rare earth elements. Several techniques such as physical separation, flotation, ion-exchange, agglomeration, and leaching are being evaluated for the successful exploitation of these elements from coal and its by-products. A previous study published in the Geoscience BC 2018 mineral report on the characterization of REE in the British Columbian coal samples have shown that a major portion of the rare earth in the run of mine coal reports to the middling and tailing streams. Hence, this study is focused on the extraction of the rare earth from coal tailings. Several studies have shown the use of an alkali-acid leaching process to successfully demineralize various high ash coals to produce a clean coal concentrate since the ash-bearing components such as clay and quartz were removed from the coal during this process. In this study, the alkali-acid leach process was adopted to chemically clean coal tailings as well as to extract rare earth elements. Different process parameters such as sodium hydroxide (NaOH) concentration, temperature, and time were studied. Results showed that it is possible to extract more than 85% of REE with this process and simultaneously produce clean coal from coal tailing.

Analysis of a coal preparation plant. Part 2. Effect of water quality on flotation performance

This manuscript is an extension of part 1 in which secondary data was acquired and analyzed to evaluate the effect of the water management system and recycling water on the performance of a coal preparation plant. Recycling water leads to an accumulation of inorganic electrolytes by dissolving some of the inorganic matters from the coals. The effect of water quality on the performance of a Jameson cell at a coal preparation plant was investigated using water conductivity and pH data monitored for approximately two years over a three year period. The concentration of inorganic electrolytes was found to strongly affect the gas dispersive properties in the flotation cell and the dosing of other reagents was modified in response to variations in the conductivity of the water. Flotation performances were assessed by the average particle density of the tailings stream. The results again highlight the significant effect of the presence of inorganic electrolytes. Specifically, the interaction of the conductivity with the frother concentration and the superficial gas velocity could lead to the increased flotation of coal particles as well as the entrainment of coal reject particles.

Analysis of a coal preparation plant. Part 1. Changes in water quality, coal seam, and plant performance

Coal preparation plants are under increasing pressure to reduce their consumption of fresh water leading to the use of recycle water. Recycled water generally contains a large quantity of dissolved inorganic electrolytes, which affect coal flotation. This paper reports the conductivity and pH measurements of water in the tailings stream of an industrial scale flotation cell covering a period of approximately two years. The different coal seams processed at the site were also compared and the influence the water quality on the overall yield of coal assessed. This study presents the large variation in inorganic content in recycled water observed for a wash plant and determines its possible effect on coal preparation. The maximum daily temperature was found to be an important factor controlling the amount of inorganic electrolytes in the water and, very significantly, the water management system implemented. The overall plant performance was somewhat affected by the use of water containing high concentrations of inorganic electrolytes. The effect of the quantity of ions in the water on the flotation process is explored in Part 2.

Selective separation of copper and nickel ions from aqueous solutions containing calcium by emulsion liquid membranes using central composite design

AbstractThe emulsion liquid membrane technique was utilized to selectively extract copper and nickel from a synthetic aqueous solution containing calcium, which was used to mimic a tailings stream found in the Sudbury region of Canada. The results showed copper and nickel ions were successively extracted from the synthetic solution. Two central composite designs and an analysis of the experiments were used to optimize the process and determine the main effects and interactions of experimental factors. In the first stage, copper was extracted with a minimum removal of nickel and calcium. It was found that under optimum conditions 98 % of the copper was extracted, with only 0.9 % of the nickel and 1.3 % of the calcium being extracted. The subsequent copper stripping efficiency was 95.7 %. In the second stage, the remaining aqueous solution was treated to remove nickel with minimum calcium removal. During this stage, the corresponding nickel and calcium removal percentages were 99.0 and 0.55 %, respectively, with a nickel stripping efficiency of 84.1 %. Laboratory bench‐scale tests using a two‐stage mixer‐settler showed a good correlation with these results when moving to a semi‐continuous process, which extracted 99.7 % of the copper and 98.2 % of the nickel, with only 2.2 % calcium extraction.

Coarse chalcopyrite recovery in a universal froth flotation machine

A new froth flotation machine has been developed, known as the NovaCell, which can recover mineral particles over a wide particle size range, from the lower limit of flotation, to an upper limit which depends on the liberation characteristics of the ore. In a single device, the collection of the fines and the coarse particles takes place in separate environments. The finest particles are contacted with bubbles in a high-shear aerator, while the coarse particles are captured by bubbles in the gentle environment in a fluidised bed.In this paper, the flotation of a porphyry copper ore in the NovaCell is described. The head grade was 1.0% Cu, and the copper mineral was freed from encapsulation at a relatively coarse size. The initial grind size was 600 µm. Tests were conducted in a laboratory unit, in both batch and continuous modes, using a conventional reagent suite. The data were analysed, and rate constants were established on a size-by-size basis. The rate constants for the batch and continuous modes were consistent. They were used to predict the performance of a bank of similar cells in series. It was found that with four rougher NovaCells in series, and a cleaner circuit, it would be possible to obtain copper recoveries above 99%. Approximately 80% of the feed is rejected as coarse gangue particles from the roughers, thereby reducing the load on the secondary mills preparatory to the cleaner circuit. The savings in operating costs of grinding energy and media, are estimated to be 40% approximately.The NovaCell delivers two tailings streams, one of which has been de-slimed in the fluidised bed. It can be drawn from the Cell at a high percent solids, and is suitable for dry stacking without further dewatering. The test program uncovered a number of interesting features relating to the distribution of copper in the feed on a size-by-size basis, and to the maximum recovery at infinite residence time as a function of particle size, which will be described.

Development of a new fine particle dry separator

Dry coal cleaning has generated renewed interest in scientific and coal mining communities alike due to water scarcity in many parts of the world and the numerous tailings ponds that have resulted from traditional wet coal preparation methods. Commercially available dry separation technologies such as air tables and air jigs are mostly effective in cleaning coarse coal with particle size larger than 6.35 mm. The smaller-than-6.35 mm fraction, which might be up to 20 to 40 percent of raw coal, is sent to the clean coal or tailings streams in a dry separation plant without any cleaning. The main objective of this study is to develop, design and fabricate a new density-based dry separator to effectively clean fine coal in the size range of smaller than 6.35 mm to larger than 1 mm. A difficult-to-clean coal sample with particle size smaller than 6.35 mm and flat-shaped shales as main rocks were used in this study. Using a laboratory-scale fluidization bed, the optimum air flow rate for fluidization of fine particles in air tables was found, which was much less than that for coarse coal. The perforations diameter and open area of the separating deck of the air table were also found to be critical for fine particle separation. These findings led to the development of a new air table named SIU Airtable for cleaning fine coal sized smaller than 6.35 mm and larger than 1 mm. The new air table has a unique air distribution and fluidization system for fine particles, along with adjustable vibration frequency and direction. It also has an optional extended section to lower the moisture content of high-moisture fine coal using part of the fluidization air. The experiments showed that an ash rejection of about 49 percent could be achieved with a combustible recovery of around 89 percent, indicating suitable separation. Furthermore, increasing ash rejection to 70 percent gives a combustible recovery of 72 percent, indicating that the separation performance of the new air table is close to the fine coal washability data.

Canadian pyrrhotite treatment: the history, inventory and potential for tailings processing

ABSTRACTCanadian nickel-copper ore deposits have been a major source of nickel, copper, cobalt and precious metals for more than 120 years. The two main minerals of interest, pentlandite (Pn, (Ni,Fe)9S8) and chalcopyrite (Cp, CuFeS2), are usually accompanied by large quantities of pyrrhotite (Po, Fe1-xS). Until the 1950s, Po containing small amounts of nickel was routinely smelted as part of the valuable Ni concentrate. The rapid growth in Ni demand following World War II created impetus to treat the Po separately. This action would liberate a valuable smelting capacity for higher value Pn and recover Ni, Fe, S and energy. The Ni industry would then have a more sustainable process. Both Inco (now Vale) and Falconbridge (now Glencore) developed processes and built large industrial plants for this purpose that operated with some success. But technical issues and tenuous economics were continual challenges. By the early 1980s, these industrial operations were closed and Po containing up to 1%Ni became a waste material reporting to the tailings stream. As part of a major study on possible processing methods of Po for both value recovery and waste remediation, this paper presents a historical perspective on Canadian Po tailings with regard to their inventory.

Two-stage fast flotation of coal tailings using reflux flotation

Low pulp density and low grade slurries in the coal and minerals industries are discharged as waste to tailings dams, incurring significant losses of valuable particles. This paper investigates the rapid processing and cleaning of hydrocyclone overflow coal slurry using two laboratory scale Reflux Flotation Cells in series as a means to economically beneficiate low quality tailings streams. The Reflux Flotation Cell incorporates a novel arrangement of inclined channels to enhance bubble-liquid segregation, enabling extremely high gas rates and liquid rates per unit of vessel area. Hence, in the first stage, fast flotation is employed to rapidly recover fine coal particles using a feed flux of 11.4±0.5cm/s, up to an order of magnitude increase in the throughput rate over conventional flotation systems. First stage product was then sent to a second stage for counter-current washing using fluidisation wash water to produce a fully deslimed product, having ash percent in agreement with the minimum ash attainable using flotation as determined through tree flotation analysis. The results demonstrate the potential for two-stage Reflux Flotation to deliver high throughput at a high separation efficiency from low quality slurry, with a fivefold reduction in the required vessel footprint, thus overcoming the principal economic deterrent of having to install banks of large-scale flotation cells.