Conventional Flotation Methods Research Articles

Effects of micro- and nano-bubbles on the flotation separation of unburned carbon from coal fly ash

ABSTRACT Nanobubble technology has found extensive use in enhancing the flotation efficiency of various minerals. The utilization of nanobubbles in flotation encompasses bulk nanobubbles, surface nanobubbles, and microbubbles; however, a comprehensive comparison of their respective roles is lacking. Furthermore, there is a dearth of studies on employing nanobubble systems in the flotation of coal fly ash. The coal fly ash characters were initially studied to reveal its ultrafine size (d50: 24.80 μm) and porous structure that includes a multitude of hydrophilic functional groups. These attributes contribute to the inadequate hydrophobicity of unburned carbon within the ash. Subsequently, the effects of different collector types, frother types, and air flow rates on the efficiency of carbon removal using conventional flotation methods were examined. Comparative analysis showed that conventional flotation using diesel oil outperformed that which employed kerosene as the collector. Additionally, higher carbon removal efficiency was achieved using MIBC, with a longer carbon chain length, as the frother, as opposed to sec-Octyl alcohol. Furthermore, a direct relationship between air flow rate and coal fly ash flotation performance was observed – higher air flow rates corresponded to improved flotation outcomes. Finally, a comparison between conventional flotation and nanobubble-assisted flotation (utilizing bulk nanobubbles, surface nanobubbles, and micro-nanobubbles) was conducted. Remarkably, micro-nanobubble flotation yielded the most promising results, with the lowest loss-on-ignition in flotation tailings (3.15%) and the highest removal efficiency of unburned carbon (85.01%). These findings satisfied the loss-on-ignition requirements of Grade I fly ash standards.

Development of a new generation flotation cell and monitoring of air bubbles

Abstract The flotation process allows particles and oil to separate from wastewater with high efficiency. Therefore, it is widely used in engineering and is a multidisciplinary field of study. In this study, a new generation flotation method is developed as an alternative to conventional flotation methods. Some experiments are conducted to determine the performance of this new system. It is known that the air-demand rate in the flotation process directly improves flotation performance. For this purpose, maximum aeration efficiency and bubble properties in the flotation cell supported by the newly developed head gated conduit are examined. A pilot-scale flotation system is installed for the experimental study. With the help of high resolution and high-speed cameras, parameters such as air bubble density, air bubble size, dead zone volume and penetration depth are determined. In addition, the images recorded during the flotation process are examined with professional image processing techniques. Experimental results showed that the Froude number, jet plunge angle and cell water levels have a significant impact on air-demand in the new system.

Influence of hydrodynamic cavitation pretreatment on coal flotation

The flotation of fine coal particles has been a long-standing challenge in coal processing industry. In this study, the influence of hydrodynamic cavitation pretreatment (HCP) on coal flotation was investigated. A special HCP experiment system was designed for the conditioning of pulp based on the cavitation phenomenon through a venturi tube. Flotation results indicate that, compared with the conventional flotation method, HCP increases combustible recovery of concentrate by about 5%, besides, 50% collector dosage or 25% frother dosage can be saved with HCP under the same combustible recovery of concentrate. Meanwhile, HCP enhances the flotation rate constant by 9.41%. The sieving analysis of flotation products reveals that HCP flotation has a better response for fine coal particles relative to that of coarse coal particles. The bubble observation tests confirm the existence of micro-nano bubbles generated by HCP and the selective generation of micro-nano bubbles on the surface of coal. In addition, HCP leads to an obvious improvement of dispersion of collector. The aggregation of fine coal particles caused by HCP is another important contribution for the coal flotation. [Received: May 18, 2019; Accepted: March 28, 2020]

Dynamics of Cellular Factors of the Immune System of Arctic Foxes (Vulpes lagopus) on the Background of Mixtinvasion

The article presents data on the dynamics of cellular immune system factors of the arctic foxes (Vulpes lagopus) while being affected by mixtinvasion of protozoa (Isospora vulpina) and helminth (Toxascaris leonina). The changes in the blood cell composition, in particular those responsible for the body’s immunity and immune status, reflect the pathological effect of the endoparasites on the animal’s body. The development of the invasive process during mixtinvasions causes and is accompanied by a decrease in the level of nonspecific resistance of the host organism. In addition, a significant process of inhibition of the lysozyme complementary activity in the blood serum and the development of secondary immunodeficiencies is observed. The aim of our work was to study the development of the pathological process in arctic foxes, caused by previously detected mixtinvasion by eimeriidoses and helminthiases, as well as to identify dynamical patterns of the immune system cellular factors. Intravital diagnostics of parasitoses was carried out by means of coproscopic studies with the help of conventional flotation methods. 127 arctic foxes participated in the experiment. Among them individuals with double invasion, an invasion with both protozoa (placeI. vulpina) and helminth (T. leonina), were selected for the experiment. Healthy animals served as the control group. Arctic foxes which took part in the experiment were divided into three groups of 10 animals each. Groups were formed by the method of balanced analogous groups. Evaluation of the T-system of immunity was carried out by the method of spontaneous rosetting according to Jondal (1972). Isolation of lymphocytes by the method of A. Boyum (1968), B-lymphocytes were determined by the method of E. Mendes (1973), theophylline-resistant and theophylline-sensitive T-lymphocytes were determined using the method of S. Limatibul et.al. (1978). The immunoregulation index was calculated by the ratio of T-helpers to T-suppressors. During the experiment, it was found that in infected animals the total number of lymphocytes was significantly 10.2 % higher than in animals in the control group, however, there was a tendency to a sharp decrease in the total number of lymphocytes in patients with I. vulpina + T. leonina. The T-helper dynamics in infected foxes was 18.9 ± 0.9 (P≤0.05), which is 21.9 % less than in the control – 24.2 ± 0.6 (P≤0, 05). The dynamics of T-suppressors turned out to be directly opposite to the dynamics of the T-helpers. The dynamics of B-lymphocytes in the 2nd group turned out to be 1.76 times higher than in animals from the control. In the 3rd group same indicator was comparable with the control values of 2.9 ± 0.3, against 2.5 ± 0.4 in the control group. The study showed that mixtinvasion with placeI. vulpina + T. leonina leads to immunosuppression in the arctic foxes. Interestingly the specific therapy did not straighten the immune state of the animals, but on the contrary it became more pronounced, which suggests that antiparasitic drugs have an immunosuppressive nature on the body of arctic foxes as evidenced by violations of the parameters of the body’s natural resistance, the content of T-E-ROCK lymphocytes.

Improving Coal Flotation by Gaseous Collector Pretreatment Method and its Potential Application in Preparing Coal Water Slurry

Low-rank coal is difficult to upgrade using conventional flotation methods due to its high hydrophilic properties. Thus, it is necessary to explore new methods for upgrading and utilizing low-rank coal. In this investigation, a gaseous dodecane pretreatment method was used to enhance the flotation performance of low-rank coal. Pore distribution analysis, FTIR (Fourier Transform Infrared Spectroscopy), and contact angle measurements were used to study the surface properties of the coal sample. Size distribution and float-sink test results indicated that the coal sample contained a lot of clean coal with low ash content, which could be used as a high quality raw material for making coal water slurry. FTIR, pore distribution analysis, and contact angle results showed that the coal was very hydrophilic due to the high concentration of -OH group and the large number of pores and cracks on the coal surface. The hydrophobicity of the coal sample was significantly improved by the gaseous dodecane pretreatment method. Clean coal with 67.2% combustible matter recovery and 10.5% ash content was obtained by gaseous dodecane pretreatment flotation method. Coal water slurry with 60% concentration was prepared using the flotation clean coal.

Leaching of a Tailings from Oxy-sulfur Copper Ore with Sulfuric Acid

In this paper, mineralogy and leaching comprehensive utilization of tailings from an oxy-sulfide copper ore were studied. Tailings grade was 0.526%, of which copper was primary free copper oxide. Malachite was not completely dissolved although it flake aggregate size was much larger than other minerals. When the tailings were ground again to a fineness of -0.074 mm 93.5%, the copper grade in the tailings could only be reduced to 0.489% after one roughing and two scavenging. It was difficult to effectively recover copper with conventional flotation methods. Under the pulp concentration of 33%, the pulp temperature of 45 °C and 55 °C, sulfuric acid dosage of 160 kg/t, leaching time of 0.5 h, immersion liquid contained copper 2.37 g/L, the leaching rate of 91.34% was obtained with acid leaching, which the copper tailings got effectively recycled.

Effect of Oleic Acid on Froth Properties and Reverse Flotation Performance of Thermal Coal

Reverse flotation was proposed as a potential method for the upgradation of low rank thermal coal. Higher combustible matter recovery in the float could be obtained using reverse flotation method compared to conventional flotation method. In order to reduce the entrainment of fine particles, oleic acid (OA) was used as froth regulator in coal reverse flotation process. Experimental data showed that the total volume of froth product in the absence of OA was almost 3 times more than that in the presence of 0.45 kg/Mg OA dosage. Reverse flotation results showed that the ash content of froth product increased with the increase of OA dosage which indicated that the entrained coal particles could be decreased by the addition of froth regulator OA.

Potential Processing Routes for Recovery of Platinum Group Metals from Southern African Oxidized PGM Ores: A Review

The beneficiation of platinum group metals (PGMs) from pristine (unweathered) sulfide ores has conventionally been conducted through froth flotation, which typically achieves platinum recoveries of over 85%. The achieved successes of PGM concentration by flotation from the pristine sulfide ores are largely due to the occurrence of PGMs in close association with base metal sulfide minerals like chalcopyrite, pentlantite, and pyrrhotite which are easily floatable. However, the fast depletion of sulfide PGM-bearing minerals has triggered interest in exploring the recovery of the PGMs from near-surface oxidized PGM ores which have proven to be more difficult to process by conventional means as an alternative source to sustain production of PGMs. Earlier attempts to process the oxidized PGM ores by conventional flotation methods achieved poor recoveries (typically less than 50%). The resource estimates of oxidized PGM ores which are either unmined, mined, and stockpiled or discarded as overburden waste in South Africa and Zimbabwe are over 500 million tonnes. The economic benefits that could be realized in the event of an alternative and effective processing technique being developed would be immense. This paper reviews and discusses different research efforts that have been made to improve PGM recoveries from oxidized ores, and their merits and demerits.

Recovery of Ultrafine Copper Oxide Mineral with Vacuum Flotation

Tangdan copper oxide ore deposit, located in the northeast Yunnan province of China, is the largest independent copper oxide deposit in China. The ore from the deposit is characterized by low grade, high oxidation ratio and fine-grained dissemination, which results in the poor flotation recovery. The analysis of plant flotation data reveals that the loss of copper minerals into tailings is mainly with coarse size fraction, due to its insufficient liberation and finer size, especially for the size fraction below 10 microns, which are very difficult to be floated with conventional flotation methods. In order to improve the flotation performance of the ore, laboratory tests include Hallimond flotation and vacuum flotation were respectively conducted with pure malachite, the dominant copper oxide mineral in the deposit; and the results indicate that a finer grinding fineness up to -325 mesh even -400 mesh is required to decrease the copper loss in the coarse size fraction, and vacuum flotation provides a promising way for the recovery of ultrafine malachites.

RECOVERY OF COPPER FROMAMASSIVE POLYMETALLIC SULPHIDE BY HIGH CONCENTRATION CHLORIDE LEACHING

A new process for the recovery of copper and associated base metals from a polymetallic massive sulphide ore is described. The massive sulphide contains copper and especially nickel sulphide in a mineralogical form which negates both good recovery and high grades in concentrates using conventional flotation methods. Utilizing the properties of high concentration chloride brines, a hydrometallurgical flowsheet has been developed and tested whereby the recovery of all of the metals and some of the power requirements for the plant itself can be derived from the ore. The new process involves leaching of the whole ore in two stages: 1) a primary leach during which the pyrrhotite is leached with HCl assisted by MgCl2 to yield hydrogen sulphide (from which energy is produced) and 2) a ferrous chloride solution; a secondary ferric chloride/MgCl2 oxidizing leach during which the economic metals (C, Ni and Co) are solubilized. The generated primary ferrous chloride leach solution is subjected to oxidation and hydrolytic decomposition to precipitate the excess iron as hematite and regenerate the HCl lixiviant. Copper recovery is effected via ion exchange and generation of a copper sulphate electrolyte advanced to conventional electrowinning. The Ferguson Lake deposit of Starfield Resources Inc. in Nunavut, Canada, is the subject of this paper, which focuses on the leaching and copper recovery unit operations of the proposed flowsheet.On decrit un nouveau procede pour la recuperation du cuivre et des metaux de base associes d’un minerai polymetallique massif de sulfure. Le sulfure massif contient du cuivre et surtout du sulfure de nickel sous une forme mineralogique qui empeche a la fois une bonne recuperation et des teneurs elevees dans les concentres lorsqu’on utilise les methodes conventionnelles de flottation. Utilisant les proprietes de saumures de chlorure a concentration elevee, on a developpe et evalue un schema de procede d’hydrometallurgie par lequel on peut deriver, a partir du minerai, la recuperation de tous les metaux et une partie de l’energie necessaire pour l’usine meme. Le nouveau procede implique la lixiviation du minerai entier en deux etapes: 1) un lessivage primaire durant lequel la pyrrhotine est lessivee avec du HCl assiste deMgCl2 pour produire de l’acide hydrosulfurique (a partir duquel on produit de l’energie) et 2) une solution de chlorure ferreux; un lessivage oxydant secondaire de chlorure ferrique/MgCl2 lors duquel on solubilise les metaux economiques (C, Ni et Co). La solution de lessivage primaire generee de chlorure ferreux est soumise a une oxydation et une decomposition hydrolytique pour precipiter l’exces de fer en hematite et pour regenerer le lixiviat HCl. La recuperation du cuivre est effectuee via l’echange d’ions et la production d’un electrolyte de sulfate de cuivre, avancee a l’electro-obtention conventionnelle. Le depot de Ferguson Lake de Starfield Resources Inc. au Nunavut, Canada, est le sujet de cet article, lequel se concentre sur les unites d’operation de lixiviation et de recuperation du cuivre du schema de procede propose.

Atypical and typical zinc geochemistry in a carbonate setting, Sä Dena Hes Mine, Yukon Territory, Canada

The Sä Dena Hes Mine produced Pb and Zn concentrates from a polymetallic Manto deposit in 1991 and 1992. Ownership of the mine was assumed by Sä Dena Hes Operating Corporation (Teck Cominco Ltd and Pan-Pacific Metal Mining Corporation) in 1994. Sphalerite and galena ore bodies with negligible Fe sulphide were processed by conventional flotation methods resulting in carbonate-rich tailings. This paper presents evaluations of atypical and typical Zn geochemistry under non-acidic conditions using laboratory testing, mineralogy and simple modelling. Atypical behaviour is shown by drainage containing 40 mg/l Zn from a short adit. The Zn load contained in the mine drainage is not apparent in a spring-fed stream a few hundred metres down-gradient. Results of an attenuation test to mimic field conditions showed that Zn was removed to concentrations of less than 0.001 mg/l. Spherical aggregates containing 40% Zn were found in the column residues using scanning electron microscopy. The aggregates are likely a Zn hydroxide or basic carbonate based on the Zn concentration, though the exact mineralogical form was not determined. Similarly, elevated Zn concentrations (up to 56 mg/l) have been found in pH-neutral porewaters near the water table in the tailings deposit. Zinc concentrations generally decrease to below 1 mg/l just below the water table and below 0.1 mg/l in seepage from the tailings dam. However in this case, simple dilution modelling and thermodynamic equilibrium modelling of the tailings porewater chemistry showed that the decrease in Zn concentrations could be attributed to the formation of Zn carbonate. Electron microscopy confirmed the presence of smithsonite (ZnCO 3 ) in the tailings; in addition Zn also occurred as a trace element in Mg–Mn–Ca carbonate phases.

Selectivity in the polymer assisted separation of galena from quartz by flotation

The flotation of ultrafine (< 5 μm) sulphide minerals is notoriously poor. A method of selectively aggregating ultrafine galena particles with coarse galena particles has been developed. Key features of this method include: minimising entrapment of non-values into the aggregate structure and; provision of adequate free surface to allow collector adsorption after aggregation so that separation can be achieved using conventional flotation methods. Results from particle interaction and polymer adsorption experiments are presented. Flotation experiments on mixed mineral, galena-quartz, slurries using both traditional and the newly proposed aggregation method, over a range of polymer concentrations, are reported.

Removal of organic contamination from Buffalo River sediment by froth flotation

Organic contaminants can be removed from river sediment using conventional flotation methods. Organic contamination in sediments is one of the most significant pollution problems facing the Great Lakes region. Using conventional flotation, the majority of the organic contamination can be collected in a concentrate, leaving a “clean” tailings. This provides a cost savings by reducing the amount of material requiring further treatment. The concentrate can then undergo additional flotation stages, or other contamination removal procedures, to further remove the organic contaminants.

浮遊選鉱法による石炭の脱灰特性に関する速度論的検討

The objective of this research is to develop a new froth flotation method to be employed in CWM (Coal Water Mixture) preparation. The froth flotation method is famous for practical coal cleaning, but it has some problems relating to CWM preparation. In conventional flotation method, deashed coals tend to coagulate because much oil used as a collector is included in them. Therefore, it seems to be difficult to disperse the deashed coals into water in preparing CWM. Accordingly, its important to increase the carbon recovery rate by making use of the small amount of oil.In this report, the kinetic study of carbon recovery was made using coals with wide size distribution which is suitable for CWM preparation. The flotation method used here is different from the conventional one at the point that collector is fed in the form of gas.Carbon recovery rates for various coals were found to obey the first order kinetics with respect to carbon concentration in the suspension. The rate constants were found to correlate well with the O/C atomic ratio of the coals. Coal concentration of the feed suspension had no effect on the recovery rate when it was smaller than 10%. But at higher concentration, a large decrease of carbon recovery was observed.

Séparation d'insolubles en phase liquide par électroflottation

Generally speaking, flotation relies on surface and interface tension properties to get solid particles to hook on to gas bubbles produced in a liquid. Conventional flotation methods (e.g. ore beneficiation) result in average enrichment in terms of a given constituent towards the surface, whereas the aim of polluted water treatment is to extract large quantities of fine matter after initial coarse separation. Mechanically-produced gas bubbles are too big for really effective results, but sizes as small as 0.2 mm can be produced by electrolysis, this being the limit for laminar rising flow. The most rational industrial system is one with the polluted liquid and bubble flows in opposite directions which gives the best concentration gradients and highest interception probability. The liquid passes through electrodes arranged in sheets at the bottom of the tank and the sludge is removed from the surface by mechanical means. The liquid flow velocity limit is about 4 m/h ; specific current and voltage are 100 A/m2 and 8-10 V ; the bubbles are swept over an effective depth of 0.5-1.0 m. The liquid can be prepared before treatment if required, for example by flocculation, which sometimes makes treatment more effective. The main advantages of the process are that it is very effective, easy to regulate, requires little room, gives a high sludge concentration, is economical to run and has simple conditioning requirements. For example, paper mill effluent at 1 g/l has been treated sucessfully with an input of 140 Wh/m3 without conditioning and 60 Wh/hm3) after flocculation. Residual solids in the water after treatment were less than 10 mg/l in the first case, and there were none in the second. The process is suitable for any raw or polluted water purification application and thus offers an exceptionally wide scope.

サイクロン浮選に関する研究

The cyclone flotation method as a variety of pressure flotation, can be distinguished in various respects from the conventional flotation methods by mechanical flotation machines. In the course of preliminary experiments and examinations it was found that the air-lift cyclone flotation system comprising an aerator and a separating cyclone connected by an air-lift pipe has following advantages:1) increased rate of aeration and sufficient dispersion of air bubbles by using the isolated aerator, 2) rapid and entire separation as well as sharp cutting of froth in the isolated separating cyclone, 3) increased gas precipitation effect, 4) simple structure with no mechanically moving parts, 5) low power requirement, 6) ease of constructing complex flotation circuit by common air compressor system.The authors have made further experiments to develop the aerator of cyclone type in which centrifugal shearing force is utilized effectively.Test results indicate that flotation rates can be radically increased with moderate centrifugal force in the separating cyclone.