Falcon Concentrator Research Articles

Experimental study of quartz classification in the enhanced gravity field using Falcon concentrator

The classification and separation of minerals happen in the traditional gravity separation simultaneously. This paper focuses on the classification performance of quartz particles in the enhanced gravity field. The classification efficiency of single quartz particles decreased then increased with the increase of rotational angular velocity, while it decreased with the increase of backwash water pressure. The classification efficiency of -0.5 +0.25mm, -0.25 +0.125mm, -0.125 +0.074mm, -0.074 +0.045mm and -0.045mm quartz was higher than the corresponding narrow size of -0.5mm quartz in general. The “fish-hook” phenomenon appeared in the partition curve of -0.5mm quartz under small/large rotational angular velocity and small backwash water pressure, and the dip point could be found in fine particles region, which indicated that the “fish-hook” was closely related with operating parameters and particle size. A medium rotational angular velocity and larger backwash water pressure could be helpful to avoid the appearance of “fish-hook” in fine particles region and achieve a better classification performance. This investigation is beneficial to understand the regularity of particle migration in the enhanced gravity field.

Size-Dependent Model to Determine the Effects of Operational Parameters on the Performance of the Falcon Concentrator

Size-Dependent Model to Determine the Effects of Operational Parameters on the Performance of the Falcon Concentrator

Characterization and gravity concentration studies on spodumene bearing pegmatites of India

ABSTRACT The exclusive properties of lithium make it indispensable for its diversified applications, resulting in a steep increase in the present-day demand. In the present investigation, characterization and laboratory beneficiation studies were carried out on the spodumene-bearing lithium pegmatites of India. The major minerals associated with the sample are spodumene, quartz, albite, orthoclase, and muscovite. The chemical analysis results of the collected samples show a variation of Li2O content between 0.02 to 1.85%. The gravity concentration studies were carried out on the feed material with a Li2O content of 1.10%. Gravity concentration studies following heavy liquid separation (HLS), mineral jig, shaking table, and Falcon concentrator were used to enrich the spodumene content. The sink and float analysis on feed material showed that the spodumene mineral is fairly liberated. A better separation of spodumene from the associated silicate gangue was achieved in HLS and mineral jig. Even though fine particles liberated well, separation in the shaking table and Falcon concentrators were inferior due to lower concentration criteria (CC-1.33). Further, the separation efficiency (SE) has been computed for all gravity concentrators. HLS has higher SE than the mineral jig, shaking table, and Falcon concentrator for separating spodumene from the silicate gangue.

An extraction of copper from recycling plant slag by using falcon concentrator

An extraction of copper from recycling plant slag by using falcon concentrator

Separation behavior of Falcon concentrator for the recovery of ultrafine scheelite particles from the gold mine tailings

The utilization of mining and industrial wastes is gaining importance worldwide as it is a potential resource of many valuable minerals. The present study is focused on the separation of the fine and ultra-fine size scheelite particles present in the gold mine tailings using a Falcon advanced gravity concentrator. The manuscript reveals the mechanism of separation, segregation of particles, a saturation of the concentrate bed, and the role of different process parameters in the scheelite recovery. The experimental results indicate that the formation of the concentrate bed inside the Falcon bowl constitutes mainly coarse particles in the initial interval, which are later replaced by fine heavy particles. The saturation studies, carried out using different amounts of feed, indicate that the bowl can operate with 830g of feed sample, called the critical mass, beyond which erosion of particles occurs. Considering the Falcon concentrator efficiency is greatly influenced by operating variables such as bowl speed, wash water rate, and feed rates, statistical tools have been used to evaluate the influence of the different variables on yield, enrichment ratio, and recovery of WO3 values. The results indicate that only bowl speed and wash water have a significant effect on the separation efficiency. The optimum results for all the three responses were obtained as 17.16% yield, 4.66 as enrichment ratio, 67.5% of recovery at a rotational speed of 70 Hz, and wash water rate of 4 L/min where feed rate was fixed at 1 kg/min.

Investigation of the effects of particle size on the performance of classical gravity concentration equipment

ABSTRACT The use of gravity concentrators involves several challenges, such as determination of the liberation sizes of the minerals, selection of appropriate particle sizes for the applied concentration method, and the severity of the beneficiation of fines.In this study, the effects of fully liberated (artificial mixtures of magnetite and quartz) and non-liberated particles (chromite ore collected from a chromite processing plant) on various gravity concentration equipment were investigated as a function of particle size considering recoveries, separation efficiencies, and grades of products. A series of tests were conducted on shaking tables, spiral concentrators, and a Falcon concentrator with different design features under various operating conditions. Finally, the separation efficiencies were correlated with the settling rates of the particles.The test results confirmed a certain trend in the separation efficiency as a function of particle size for each condition. The separation efficiency initially increased with increasing particle size, peaked, and eventually decreased with increasing particle size. The maximum separation efficiency attained was 90% for 141 µm particles in the shaking table and 54% for 245 µm particles in the Falcon concentrator, both of which were used to treat the artificial feed. In the spiral concentrator, which treated chromite ore as feed, the maximum separation efficiency attained was 82% for 178 µm particles.This experimental study provides data to identify the concentration behavior of particles by investigating possible separation mechanisms. Consequently, it provides an understanding of the relationships between particle size and separation efficiency in terms of settling rates, especially in spiral concentrators.

Investigation of optimal falcon parameters for clean asphaltite concentrate

ABSTRACT Asphaltite is a solid fuel formed due to the metamorphism of oil separated from its reserves by tectonic movements. The most critical components that determine solid fuel quality are ash and sulfur. Proximate and ultimate analyses were performed to determine asphaltite’s ash and sulfur content. The ash content was 45.16%, and the sulfur content was 5.81%. Ash and sulfur in asphaltite are generally very fine-grained disseminated. Therefore, it is complicated to remove the asphaltite. This study aimed to remove asphaltite’s ash and sulfur content with Falcon Concentrator. In the experiments, the solid rate of 30% and the feed rate of 1.5 L/min were kept constant. The effects of different particle sizes, various centrifugal forces, and different water pressure on ash and sulfur removal were investigated. Combustible and separation efficiencies ash and sulfur removal efficiencies were calculated for each concentrate. Optimum ash (24.26%) and sulfur (2.74%) contents were obtained in −150 µm particle size, 3 psi water pressure, and 300 G centrifugal force. It was determined that the feed’s higher heating value of 4426 kcal/kg increased to 5708 kcal/kg in the clean asphaltite. It was concluded that the Falcon concentrator effectively reduced asphaltite’s ash and sulfur content.

Beneficiation of difficult-to-wash Indian low volatile coking coal fines by Falcon concentrator

ABSTRACT The fast depleting reserves of high-grade Indian coking coal and its resultant dependence on import makes the emerging situation a fit case for exploring innovative and high efficacy techniques such as non-conventional gravity-based systems for clean coal recovery viz., advanced centrifugal gravity separators like Falcon concentrators for fine and ultra-fine coal particles processing using enhanced gravitational force. The above methodology has been adopted for low volatile coking (LVC) coal due to the high ash content associated washability characteristics and high near gravity material content. Attempt was made using laboratory Falcon SB40 concentrator for cleaning the LVC coals assaying 32.6% ash. Considering the physical properties, coal petrography and washability studies, as received coal was ground to three size fractions of –500 μm, –250 μm and –150 μm and subjected to separation in Falcon separator. Experiments were conducted using Design Expert software to evaluate the effects of four significant process variables such as feed size, pulp density, gravitational force value and water pressure. The relationship between the response functions (ash content, combustible recovery and separation efficiency) and process variables is presented as empirical model equations. Under the optimum operating conditions, LVC coal was cleaned to 18.4% ash content with 57.8% combustible recovery using Falcon concentrator.

Arguvan linyitinden kül ve kükürt uzaklaştırılmasında farklı gravite yöntemlerinin etkisinin belirlenmesi

This study, it is aimed to find out the beneficiation of Malatya-Arguvan lignite by gravity methods. First of all, the washability of lignite has been investigated with sink-float experiments. It has been determined that lignite washability from washing curves is generally difficult but may be possible with controlled washing at a density of 1.68 g /cm3. Then, to remove ash and sulfur from lignite by shaking table, spiral and Falcon concentrator tests were conducted. Clean coals are obtained from all other methods except Falcon were found to decrease in ash and sulfur content and increase in calorific value. Clean coals with the lowest ash and sulfur content were obtained with a spiral concentrator. Reichert spiral results showed that the ash content decreased from the lignite of 37.77% to 26.50% and the sulfur content from 3.85% to 2.08%. The calorific value increased from 2576 kcal/kg to 4590 kcal/kg. Arguvan lignite has very limited usage due to lower calorific value, high ash and sulfur content. Although enrichment has been carried out, it has been concluded that lignite needs to be further improved by using different methods.

Study on separation of low-rank coal macerals in enhanced gravity field

ABSTRACT In this paper, the enhanced gravity separation of maceral components was studied based on the characteristics of maceral components for low-rank coal from Shendong. Vitrinite and ash content were only 48.42 and 8.77%, respectively. Rod mill grinding showed that the optimal grinding time was 10 min based on the vitrinite content and vitrinite recovery which reached maximum 81.34 and 80.85%, respectively. Maceral separation test conducted with the Falcon concentrator showed that using optimal conditions of rotary frequency 30 Hz, feed dosage 15 ml/s and recoil water pressure 0.03 Mpa, the best vitrinite content, benefication ratio and vitrinite recovery were 67.25%, 1.16, and 72.48%, respectively. With the increase of rotary frequency or decrease of recoil water pressure, the finer particles in each particle fraction became more underflow products, and these finer particles in underflow products were all high-density products with density higher than 1.35 g/cm3. Because the content of vitrinite was higher in the coarser particles, the average particle size of the original overflow product was directly reduced by these fine particles entering the overflow product, which caused the decrease of vitrinite content and the increase of vitrinite recovery.

Application of Enhanced Gravity Separators for Fine Particle Processing: An Overview

Beneficiation of low-grade ore is of critical importance in order to meet the growing demand for coal and mineral industries. But, low-grade ores require fine grinding to obtain the desired liberation of valuable minerals. As a result, production of fine particles makes the beneficiation process difficult through conventional gravity separators. Hence, alternative beneficiation techniques are being investigated for upgradation of metal values from low-grade ores. The gravitational force effecting the separation is replaced by the centrifugal force to usher in enhanced gravity separators. The objective of the present paper is to summarize the applicability aspect of enhanced gravity separators for different mineral systems including non-ferrous, precious, ferrous, and industrial minerals. These mineral systems include run off mine ore, secondary products like tailings and plant slags, etc. For this purpose, the design, operational features, types, and separation mechanism of enhanced gravity separators, such as Falcon concentrator, Knelson concentrator, multi-gravity separator (MGS), and Kelsey Jig, are discussed. Based on our review, research scope and future possibilities of enhanced gravity separators are also proposed.

Experimental investigation on the separation capabilities and limitation of Falcon semi-batch concentrator

ABSTRACT In the present study, an attempt was made to establish the separation capabilities and limitations of Falcon Semi-batch concentrator. Experiments were performed with quartz-magnetite and quartz-ferrosilicon binary feed system. Three different feed grades of 5, 10, and 15% magnetite by weight was used to understand the sensitivity of separation efficiency against the feed grade. It was found that separation efficiency is higher for lower feed grade material. Experimental results indicate that the falcon concentrator’s performance is poor below the concentration criterion ratio of 3. The Separation efficiency of Falcon concentrator was enhanced from 15.3% to 66.1%, only by increasing the concentration ratio from 2.4 to 3.

Coal Desliming Using Annular Rinse Water Hydrocyclone

The separation of fine coal can be improved by pre-desliming, which was significantly enhanced when fine coal was processed using a Falcon concentrator, and <45-μm coal slime was removed. Ultrafine classification tests using Krebs classification cyclone with annular rinse water showed that the increase in feeding concentration negatively affected the efficiency of classification while increasing the classification size because the settling was hindered by the high underflow concentrations. The optimization experiments with response indicators of classification efficiency based on orthogonal design using Design-Expert software indicated that the optimal classification efficiency reached 91.32% with a feeding pressure of 0.03 MPa, a rinse water pressure of 0.02 MPa, and a feeding concentration of 12.5%. Meanwhile, the classification size was 49.99 μm, which agreed well with the predicted value.

Estimation of the Fluid Velocity Profile in the Stratification Zone of a Falcon Concentrator

The Falcon concentrator is capable of separating minerals in fine size classes based on their differential density. Separation of mineral particles depends upon the fluid flow characteristics and relative movement of particles in a fluid. In the present study, a fluid flow characteristic inside the Falcon concentrator was established through experimentation and modeling. The Falcon concentrator has two fluid entry points: (a) Fluid entering through gravity assisted feeding system and (b) Fluid entering through the fluidized hole on the concentrator wall. In order to identify the role of fluid entering the concentrator, a tracer was injected into the system. As per the tracer based experimentation, it was established that fluid entering through the gravity based feeding system is responsible for thin flowing film formation in the stratification zone where particles are stratified based on their relative density. The momentum balance and continuity equations were simplified for a high centrifugal force field, and the fluid velocity profile was estimated inside the thin flowing film. Estimated fluid flow profiles will help to simulate the particle trajectories inside the Falcon concentrator. The influence of rotational speed, fluid flow rate, and cone angle on the fluid velocity profile were investigated. Fluid thickness over the concentrator wall is also estimated, and it is typically of the order of ~150–200 μm.

Integrated approach for the processing of a complex tungsten Skarn ore (Tabuaço, Portugal)

The Tabuaço tungsten project, located in Northern Portugal, consists of two skarn layers, namely “Main” and “Lower” skarns, which display significantly different mineralogical and geochemical features. Both skarns contain fine-grained disseminated scheelite, but the Lower-skarn gangue is dominated by silicates whereas the Main-skarn gangue contains calcium-bearing minerals including fluorite, apatite, and vesuvianite, in close association with scheelite. Preliminary feasibility studies showed that direct separation of calcium-bearing minerals by flotation with fatty acids, which are environmentally benign, was unsuccessful due to their similar surface properties. Several routes for each skarn type were proposed with a strong focus on the Main skarn that displays the most complex mineralogical associations. Enhanced gravity separation (Falcon concentrator), high intensity magnetic separation, and flotation with fatty acids were investigated for the Main Skarn level with the objective of producing a marketable scheelite concentrate. Flotation was thoroughly investigated in terms of depressants, producing optimally a concentrate assaying 9.2%WO3 at 87.9%WO3 recovery from a ~1.1%WO3 feed, by means of a 1:1 ratio of sodium carbonate and sodium silicate. Fluorite is the most problematic mineral in flotation with fatty acids and, consequently, new fatty-acids-based collector formulations have been developed to improve the separation contrast between scheelite and fluorite, producing a concentrate assaying 14.1%WO3 with 77.1%WO3 recovery for the fully-optimised conditions. Furthermore, the performance of two types of Falcon bowls (SB and UF) were investigated and optimised for gangue minerals rejection. The Falcon concentrator was used as a desliming and pre-concentrating apparatus: one stage of Falcon SB allowed rejection of 84% of the total amount of fluorite, more than 95% of the slimes, and 85 wt% of the mass. Consequently, it improved significantly the performance of the fully-optimised scheelite flotation as the final concentrate, after one Falcon SB stage and 4 flotation stages, assayed 62.9%WO3 with 59.4%WO3 recovery, which constituted a marketable scheelite concentrate. Both the Falcon SB parameters and the number of fully-optimised flotation stages can be optimised to maximise either the WO3 grade or the WO3 recovery, regarding the product specifications. Finally, the high intensity magnetic separation allowed rejection of around 45 wt% of the total yield prior to the milling stage with only 6.0%WO3 losses, which would decrease significantly the energy consumed during the milling stage.

Application of Falcon Centrifuge as a Cleaner Alternative for Complex Tungsten Ore Processing

Scheelite (CaWO4) is one of the main raw material for the production of tungsten. It is usually encountered in skarn deposits where it is commonly associated with other calcium minerals as fluorite, apatite, and calcium silicates. Worldwide, scheelite is upgraded to the chemical grades by direct flotation, but the separation efficiency remains limited due to similar flotation behaviors of scheelite and gangue minerals with fatty acid. The only solutions used to overcome this issue involve high energy consumption or ecotoxic reagents. In the present study, a novel method based on the use of a centrifugal Falcon concentrator was investigated to perform an efficient elimination of gangue minerals and fine particles as well as an acceptable scheelite recovery enabling a decrease of the flotation reagents consumption. The performances of the two types of laboratory Falcon bowls, Falcon UltraFine (UF) and Falcon Semi-Batch (SB), were modeled using the design of experiments (DoE) methodology, which allowed to determine the best operating parameters for each bowl. The separation performances were mainly affected by the rotary speed and the pulp density for the Falcon UF and by the rotary speed and the fluidization pressure for the Falcon SB. Due to the fluidization pressure, the Falcon SB exhibited higher gangue minerals rejection with slightly lower recoveries than the Falcon UF. Overall, the optimized Falcon SB test allowed to reach 71.6%, 22.6%, 17.2%, and 12.6% for scheelite, calcium salts, dense calcium silicates, and light non-calcic silicates respectively while the desliming efficiency reached 98.8%. For comparison purposes, a classical hydrocyclone allowed to attain 89.1%, 89.3%, 79.5%, and 76.5% for scheelite, calcium salts, dense calcium silicates, and light non-calcic silicates respectively while the desliming efficiency reached 52.0%. Theses results can be used reliably to assess the separation performances of an industrial Falcon C which can be regarded, along with Falcon SB, as a sustainable and efficient gangue rejection method for complex W skarn ore, which allows the use of environmentally friendly reagents during downstream flotation stages.

Characterisation and separation of pyritic sulfur from limestone using Falcon concentrator

ABSTRACT This study was performed to investigate feasibility of employing enhanced gravity separator for beneficiation of pyritic limestone. Limestone sample primarily constituted of calcite, dolomite, quartz and pyrite which was major gangue mineral phase in samples. Pyrite is highly dispersed in limestone. Mineralogical characteristics and liberation study using image analysis was carried out to determine optimum liberation size of pyrite. Falcon concentrator removed pyrite from limestone. In the present study, Box–Behnken design of experiments with response surface methodology was applied to understand the performance behavior of fine minerals. This was done to understand effect of different operating parameters of feed and their interaction effects on performance of Falcon separator. It was found that gravity force and water pressure have significant effect on both pyrite removal and calcite recovery of limestone concentrate. Optimization of operating parameters could yield maximum pyrite rejection in form of SO3 and maximum recovery of calcite.

Processing of Superfine and Ultrafine Phosphate of a Phosphomud (Part Two)

Mineral industries in common generate a lot of rejects in the form of fines and slimes, which ultimately create environmental and social problems besides causing losses of mineral values. In view of the recent stringent policy imposed on the environment, there is an urgent need to attempt possible simple and cheap solutions to such problems. These slimes have long been considered in the industry to be unrecoverable. It has been standard practice over many years in the phosphate industry to separate and discard the fines and ultrafine particles. 
 
 In this respect, the present study shed light on the recovery of super and ultrafine phosphate of a phosphomud produced after the processing of an East Mediterranean phosphate ore. Falcon Concentrator model SB40-VFD (semi-continuous with variable frequency drive) was used in this study to recover the -32 micron phosphate fines of D50=11 micron. The effect of the main variables of the semi-continuous Falcon concentrator model SB40-VFD, including the bowl rotation frequency Hz, the fluidizing water pressure psi, and feeding rate g/min on the separation efficiency were followed up. In addition, two feeding modes based on a particle size-by-size were tried in this study: The sample was fed as a global -32 micron sample or as two fractions, -32+11 micron, and -11 micron samples. Central Composite Rotatable Design (CCRD) was applied on the Falcon separation of the -11 micron fraction with D50 < 3 micron alone to model and optimize the separation process for the two responses: the recovered phosphate grade and recovery.
 
 Results showed that the phosphate fines containing 14.73% P2O5, 15.03% acid insoluble, and 19.07% loss in ignition was recovered with grade and P2O5 recovery reaching 28.29%, and 95.97% in case of separating the overall -32 micron sample as one feed. In case of the fractionated feeding samples, the total grade and recovery reached 29.21%, and 88.42%, respectively. The application of the CCRD results showed that the bowl rotation frequency showed to have the main irreversible effect on the product grade, where the fluidizing water pressure had the main reversible effect on the recovery. On the other hand, feeding rate showed some effect on the product grade with almost no effect on its P2O5 recovery%.

Separation characteristics of centrifugal fluidized separator using binary density system

ABSTRACT Centrifugal fluidised separators play an important role in separating fine-size minerals during the beneficiation process by augmenting the gravity-assisted differential density-dependent settling process by externally applied centrifugal force. To develop a comprehensive understanding of the separation characteristics of a centrifugal fluidised separator, synthetic binary density test systems comprising of quartz and hematite were used. A semi-batch Falcon concentrator was used. The parameters of prime importance identified for this study are rotation speed, fluidising water flow rate and particle size. A set of experiments was performed and responses were measured in terms of mass recovery of hematite particles and separation efficiency. An attempt was made to develop an understanding for the separation characteristics of the concentrator by mathematical formulation. Parametric studies of separation performance were performed both experimentally and through mathematical formulations. Settling velocity, surface minimum fluidisation velocity and critical minimum fluidisation velocity were estimated for the binary density system and experimental response were examined with the help of estimated velocities.

Gold&silver recovery from jewelry waste with combination of physical and physicochemical methods

The recovery of precious metals can be successfully managed from waste which is considered to be secondary sources of raw material. Waste derived from jewelry activity falls in this category, and represents an essential component of precious metals. The most important metals in the jewelry sector are gold (Au) and silver (Ag). As a result of workmanship, the thin metals, jewel parts and metallic powders are generated and the dust produced from jewelry workshops is of great importance. This paper describes the concentration and recovery of Au and Ag from floor sweeping waste at jewelry workshops by physical (shaking table, multi gravity separator (MGS), Knelson and Falcon concentrators) and physicochemical methods (froth flotation). Experimental results demonstrated that the gravity beneficiation methods were effective for eliminating much of the waste matrix. A heavy fraction with 701 g/t Au and 6017 g/t Ag content was obtained from a feed assaying 183 g/t Au and 1835 g/t Ag by shaking table separator. For enhanced beneficiation, the middling’s from tabling were subjected to centrifugal separator and Ag grade increased from 848 g/t to 7812 g/t. Au and Ag fractions discharged in tailings from gravity and centrifugal separations were successfully concentrated using froth flotation and led to a total recovery around 92% both for Au and Ag.