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By M. Polat

Variations in flotation rate by particle size and specific gravity have been investigated for three different bituminous coals. The flotation rates for various components were determined by separating the products of bulk flotation into size-specific gravity fractions. The effects of feed size and reagent addition on the flotation response of individual size-specific gravity fractions were evaluated.

Jan 1, 1994

By David X. Zhang

This paper describes the results of using shear flocculation and flotation known as aggregative flotation technique for the enrichment of coal-derived char produced from mild gasification process. Aggregative flotation is a separation process which involves the use of suitable aggregating liquid under the action of high shear forces to render hydrophobic surface of coal-derived char particles to aggregate in an aqueous slurry. The fine carbonaceous particles are aggregated into larger floes while the impurities remain hydrophilic. In subsequent flotation process, the char aggregates are then separated from mineral matters by aeration in the flotation cell. The floatability of char aggregates and removal of mineral matters from chars are studied in a lab scale flotation column cell. The effect of various operating parameters on the aggregative flotation responses is presented. Emulsification of aggregating liquid using high intensity agitation and ultrasonic energy provides excellent aggregating liquid dispersion and increases selectivity for char aggregation. In subsequent flotation process, it results in significantly increasing the flotation rate of char aggregates. The microscopic examinations of bubble attachment to coal-derived char particles under various aggregating liquid dispersion levels were conducted by induction time measurement. The distributions of hydrophobicity of char particles and char aggregates prepared under various aggregating liquid dispersion techniques were measured by film flotation. The char particles prepared under high intensity emulsification attach at significantly faster rates to air bubble and with lower mean critical wetting surface tension than that of char with direct aggregating liquid addition. An interrelationship of increasing in flotation rate/combustible recovery with decreasing in induction time, mean critical wetting surface tension and dispersion of hydrophobicity on the char particles and char aggregates were obtained.

Jan 1, 1992

By R. S. Wang

The flotation of pyrite which be pretreated by electrochemical ways under external controlled voltages in different pH is explored. The floatability of pyrite is increased indistinctively after being pretreated in acidic and xanthate environment; Whereas, it is increased obviously between 400~800 millivolt in alkaline and xanthate condition. The reason for higher recovery of pyrite is that oxida-tion reaction, which results in S0 and S02, takes place on its surface, and that ethyl xanthate is oxi-dized into dixanthogen. In the meantime, the kinetics and mechanism is also studied.

Jan 1, 2014

By Joshua Cole, Joshua Sovechles, Christian Cardoso, Guillermo Bermudez, Martta Hirsi, Joshua Dettamanti, Rabia Abbasi

The implementation of technological advancements in flotation is key to optimize performance in mining operations. Consequently, flotation cell’s performance is highly dependent on the effectiveness of the mixing mechanism. A more efficient flotation mixing mechanism is likely to improve metallurgical performance and optimize energy consumption, which is the motivation for Metso’s journey to develop the latest iteration of FloatForce®. Looking to test the new design at plant scale, Metso approached the Kennecott Copperton concentrator, which is continuously looking for different venues to improve metallurgical performance. In this context, a test campaign was conducted to implement this new flotation mixing mechanism in their rougher circuit during 2024. The industrial trial consisted of several sampling campaigns assessing different operational parameters for comparison purposes around a 300m3 flotation cell. The effect of the new flotation mixing mechanism on the cell’s power draw was also studied. The results of this trial at Kennecott are presented in this paper. Overall new flotation mixing mechanism, FloatForce+ was seen to perform as well as the original FloatForce.

Feb 1, 2025

Although mining, particularly of gold and coal, played a significant role in the development of New Zealand, from the time of the spectacular gold rushes of the 1860s its economic importance to the country as a whole has decreased substantially since that time. Gold, coal and non-metallic agricultural and industrial minerals have been found in economically significant quantities, however, the search for base metals has not been successful.

Jan 1, 1982

By Max Kraut

UNTIL VERY RECENTLY the flotation process has not found much application in the treatment of gold ores. No appreciable improvement has been made lately in the technology of this application; but the possibilities of flotation have been more fully appreciated. Excellent results were obtained long ago, but few operators paid much attention to them. For instance, in 1915 extensive experiments were carried out by Mr. Beauchamp and Minerals Separation on ores from the Dutch-Sweeney mine near Jimtown, Calif. The ore contained gold-bearing pyrite and laboratory tests indicated a 10c. tailing on a $6 head. In 1918 a 300-ton flotation mill using Minerals Separation machines was built based on the results obtained. However, when the mill began full-scale operation, mill heads did not come up to expectation, being only $4; also the-tonnage was considerably less than had been expected. Flotation mill tailing assayed 15c., indicating a recovery of over 96 per cent, so that excellent metallurgical results were obtained. The operation was a success but the patient died.

Jan 1, 1932

By D. S. Loubser

The technique of backfilling in the gold mining industry is dependent on the dewatering of slurry to form a solid support system. In many cases flocculants are added to the slurry to increase the rate of dewatering. To ensure that a stable support is obtained it is important that the chemistry, application and limitations of these flocculant additives are understood. Flocculant additives have to be added at a point where minimum shear will occur. (Shear occurs when a flocculant is exposed to excess energy resulting in breakdown, of the floc.) To ensure that optimum results are obtained it is important that personnel involved are trained to use the flocculant additives and dosing equipment correctly.

Jan 1, 1988

By H. L. Ford

Flocculant testing should be initiated for economic or performance reasons. When the decision has been made to test, the laboratory can provide valuable information concerning the various products under consideration. Properly conducted laboratory tests can determine: 1. If two flocculants are needed to achieve clarity or density. 2. Ease of mixing. 3. How quickly the material goes into solution. 4. Stability of prepared f locculant solution. 5. Stability of the floc formed. 6. Amount of mixing required for proper floe formation. 7. Optimum flocculant concentration. 8. Optimum pulp density. 9. Approximate location of the point of addition. 10. Single or multiple addition points. When a flocculant shows promise in the laboratory, a plant test should be scheduled. During the plant trial, arrange for normal conditions and start testing with a crew that is most familiar with the unit operation where the flocculant will be applied.

Jan 1, 1986

By John Ralston, Jona Addai-Mensah, Patience Mpofu

The flocculation and dewatering behaviour of kaolinite (non swelling) and smectite (swelling) clay dispersions has been investigated using hydrolysable metal ions Mn(II) and Ca(II) and anionic polyacrylamide-acrylate copolymer (PAM) at pH 7.5 and 10.5. A pH-dependent, specific metal ion adsorption behaviour, accompanied by a marked reduction in particle zeta potential and slurry shear yield stress, was observed to have a profound influence on the colloid stability of both types of clays. Due to the differences in the cation exchange capacity, the smectite clay dispersion required a higher amount of metal ions than kaolinite dispersion to produce similar effects. The adsorption density of the anionic PAM at the negatively charged clay particle surfaces correlated well with metal ion hydrolysis and adsorption behaviour, all of which had a strong effect on slurry settling rate and extent of consolidation. At pH 7.5 where Mn(II) ions hydrolyse, metal ion and flocculant adsorption densities were both greater in the presence of Mn(II) than Ca(II) ions. At pH 10.5, however, where Ca(II) ions begins to hydrolyse, higher adsorption densities were observed for Ca(II) ions in comparison with Mn(II) ions, as the latter hydrolysed completely and precipitated. The metal ion mediated flocculant adsorption led to improved hydrogen bond driven particle bridging and facilitated charge neutralisation flocculation mechanisms which significantly enhanced the dewaterability of both clay dispersions.

Jan 1, 2003

By S. K. Kawatra, H. Haselhuhn

"In many mineral processing applications it is necessary to know the isoelectric points of the various minerals in the ore to properly perform flotation and other mineral separations. However, current zeta potential analysis technology used to determine the isoelectric point of a particle suspension cannot deliver the isoelectric point of each individual mineral, just an average of the mineral system. Traditionally, individual isoelectric points have been gathered by testing pure, synthetic minerals. These values can vary widely depending on the mineral synthesis procedure and the water quality used during the isoelectric point analysis. A more robust approach for determining the actual isoelectric point of a particular mineral in a mixture of minerals is needed. This paper details a method for determining the isoelectric point of an iron oxide mineral in a siliceous iron ore. The method uses a laser scattering particle size analyzer and a pH electrode to determine the pH at which the liberated mineral particles begin to flocculate as pH is decreased. The pH at which the average particle size rises dramatically is the isoelectric point of the mineral with the highest isoelectric point in the ore. This measurement technique was used on natural hematite, goethite and siderite ores as well as a synthetic mixture of pure silica and pure hematite. The results for synthetic hematite mixtures were comparable to literature values.IntroductionRecently there has been an increased interest in the processing of low-grade iron ores (Bolen, 2014; Carlson and Kawatra, 2008, 2011, 2013; Halt et al., 2014; Halt and Kawatra, 2014; Haselhuhn 2012, 2013; Haselhuhn et al., 2012a, 2012b; Kawatra and Halt, 2011; Liu et al., 2014; Manouchehri, 2014; Sandvik and Larsen, 2014; Semberg et al., 2014). The zeta potential of iron ore minerals is a very important and often overlooked aspect of iron ore mineral processing. Zeta potential is the charge at the shear plane of a surface in an aqueous environment (Carlson and Kawatra, 2013). Many ores consist of a variety of minerals differing in zeta potential. This property of a particle surface in water is responsible for either keeping the particles dispersed from each other or flocculated to each other. This is important during many operations such as flotation, desliming and thickening. Zeta potential is primarily a function of the pH of the water and the mineralogy of the particles, though certain ions within the water can also have a significant impact (Haselhuhn, 2012). Consider the following situation: silica (SiO2) particles and hematite (Fe2O3) particles are suspended in an aqueous solution. These two types of minerals have drastically different zeta potentials throughout the pH spectrum (Esumi et al., 1988). In alkaline conditions, both types of particles exhibit negative zeta potentials and will tend to disperse from each other. In acidic conditions (between pH of 3 and 6), silica has a negative zeta potential while hematite has a positive zeta potential, so these surfaces will tend to be attractive to each other and the particles will flocculate and settle. This phenomenon is visually described in Fig. 1. The pH at which the two minerals begin to attract to each other, or destabilize, is near hematite’s isoelectric point. The isoelectric point is defined as the pH at which the surface has a net zero zeta potential (Carlson and Kawatra, 2013)."

Jan 1, 2015

It has been reported previously that dolomite samples from different locations showed varying flocculation behavior with Poly(ethyleneoxide) (PEO). In this study it is determined that palygorskite associated with the Florida dolomite samples is responsible for their flocculation with PEO. A detailed characterization of the dolomite samples from different locations and its relevance to flocculation with PEO is discussed.

Jan 1, 1994

By Vladko Panayotov, Marinela Panayotova

"Recently, in order to extract metals, the industry is trying to process old metallurgical slag. The material requires very fine grinding that results in enhanced slime-formation. This in turn leads to problems in the course of the flotation process and to a loss of metal. In addition, it causes difficulties in the wastewater treatment aimed at water reuse. The aggregation and separation of the fine particles and their further subjecting to mineral processing would result in more efficient use of raw materials. Closing the water cycle also would be facilitated. The paper presents results from studying sixteen flocculation reagents, commercially available for treating municipal wastewater, including products based on nanotechnology, for their ability to rend the production wastewater in suitable for reuse in the flotation. It turned out that, from all studied reagents, the cationic C-587 is suitable for the purpose. Some of reagents were studied for their ability to flocculate selectively, in presence of coke fines, rich in copper fines which are produced at grinding of a slag from lead-zinc metallurgy. Most promising reagents are chosen, based on the chemical analysis of the flocculated materials. Open-cycle rough copper flotation experiments with the flocculated fines and recycled wastewater gave encouraging results."

Jan 1, 2014

By H. Suharyono

A laboratory investigation of flocculation following polymer addition during slurry flow through pipes and in-line (static) mixers is described. Results are presented showing the effects of flow velocity, pipe length, in-line mixer elements and the use of multiple addition points on flocculation performance as measured by settling rate and supernatant turbidity. The effects of agitation and mixing time are shown to be generally consistent with the results of equivalent tests, both batch and continuous, conducted in stirred tanks.

Jan 1, 1995

By K. N. Han

Coal is becoming increasingly important as a major energy source in the face of the world's depleting energy mainly based on oil reserves. Coal is by far the most abundant fossil fuel both in the United States and abroad. Currently, because of increased mine mechanization, the fineness of preparation plant feed is increasing. Further, in the future as the grade of coal diminishes and the sulfur content increases, upgrading preparation of coal is very important. Because the density of coal is less than that of rock materials that occur as impurities, coal is separated from such waste largely by gravity-controlled processes for particle size between 5 inches and 28 mesh. If the size of coal particles is below 28 mesh, froth flotation is a good method for upgrading fine coal. Previously, numerous investigators have tried to upgrade coal values by froth flotation(1-16) and have achieved moderate success. However, the recovery and grade of coals in the concentrates are not always satisfactory, especially when the particle size is small. In general, when the size of coal is below 100 mesh, the above methods suffer from poor grade and low recovery. The reason for this is that as size decreases, the effects of gravity diminish, and other forces take effect.

Jan 1, 1985

By A. M. Raichur

Flocculation of fine coal is usually accomplished with the addition of commercially available organic flocculants. Recently it has been shown that biopolymers derived from microorganisms can be used to flocculate coal. The biopolymers flocculate coal efficiently and render the coal surface hydrophobic. The increase in hydrophobicity can be utilized either to separate the coal flocs from mineral matter. It can also be used for reducing the moisture content of fine coal. In this regard, flocculation and settling tests of fine coal with biopolymers and synthetic flocculants was undertaken and the results are discussed here. Also, a transport model was developed for the time-dependent settling tests for fine coal.

Jan 1, 1996

By B Scheiner, D. A. Stanley

Introduction Treatment of ores to recover metal and mineral values results in waste materials usually in the form of dilute slurries. The US Bureau of Mines (USBM) investigated a technique for dewatering phosphatic clay waste by flocculating with polyethylene oxide (PEO) and dewatering the resulting floes on a static screen and/or trommel screen (Schemer et al., 1985). In the investigation, it was determined that PEO was far superior to polyacrylamide polymers for this type of dewatering. This paper discusses reasons for this superior performance. Comparison of PEO with polyacrylamides Dewatering experiments were conducted by adding PEO solution from a burette to a stirred clay slurry. The dewatering endpoint was characterized by rotation of the floc mass as a unit, a clear supernate, a maximum floc size, and a minimum floc volume. Additional water was removed from the floes by hand squeezing (Schemer et al., 1985). The clays investigated were sodium, potassium, magnesium, calcium, and aluminum exchanged montmorillonite and attapulgite. Nine commercially available (Superfloc) polyacrylamides were compared with PEO at two polymer concentrations. Results are summarized in Table 1. The solids content of the dewatered clays ranged between 24% and 33% and was highest for PEO-treated material. These results and the data in Table 1 indicate that PEO is superior to polyacrylamide in terms of polymer dosage required. Superflocs 16 through 128, like PEO, are nonionic and should give similar results to those for PEO if the flocculation mechanism is the same for both type polymers. Superflocs 204 through 214 are anionic with increasing anionic character from 204 to 214. Generally, the anionic polymers gave the best results for the polyacrylamides tested, but in terms of dosage they were not as good as PEO. Correlation between flocculation and dewaterability of waste slurries The overall mechanism for mechanically induced clay dewatering is not completely known, but certain observations can be made. For instance, when a polymer is adsorbed on a clay such as montmorillonite, the polymer desorbs interlayer water. Polymer adsorption is driven by favorable entropy changes associated with this water desorption. It is also known that the -CH2-CH2- links of the PEO chain are sufficiently hydrophobic to lead to physical adsorption of the polymer (Theng, 1979). For montmorillonite slurries, the sheet-like fundamental particles, called tactoids, consist of a small, variable number of aluminosilicate layers together with interlayer water and exchange ions. The flocculation process consists of adsorption of polymer on the tactoid. Loops and tails of polymer that extend into solution then adsorb on another tactoid, forming a bridge. Mechanical action, induced by hand squeezing or in a trammel, joins the bridged tactoids face-to-face and edge-to-edge to form regions of high density. Similar orientation effects are observed for the needle-like attapulgite crystals (Schemer et al., 1985). Proposed flocculation model Generally, statements concerning flocculation and dewaterability apply to both PEO and the polyacrylamides. However, PEO has additional interaction with the clay material when compared with polyacrylamides. PEO is a polymer with repeating -CH2-CH2-O- groups and interacts with montmorillonite through a water bridge whose strength is greatly influenced by the exchange ion. To obtain insight into this interaction, a series of experiments were conducted in which different ion exchange forms of montmorillonite and attapulgite clays

Jan 1, 1987

By H. A. Hamza

An experimental study of the settling characteristics of a washery effluent originating as tailings from a froth flotation circuit was undertaken by using a systematic approach to select the most appropriate flocculant(s) under predetermined conditions. Selection and evaluation procedures which greatly reduce the effort required to select flocculants are described. The results show that, although different flocculants display superiority at different ranges of dosage. Separan MG 700 (Dow) is the most suitable on absolute economic grounds. Flocculant evaluation is based on a Cost Performance Index (CPI) which expresses the cost of flocculant (¢/ton) required to produce a unit settling rate (in./hr). From experiments carried out with a number of flocculant aid and flocculant combinations, it was concluded that the use of flocculant aids can be economically justified only if the settling rates required are higher than those obtainable at the optimum flocculant dosage. Otherwise, the value of the flocculant aid appears to be limited largely to the reduction of supernatant turbidity.

Jan 1, 1979

With the ambitious target of adding another 2,00,000 MW of power generation by the year 2017 in India the demand for coal is bound to grow. The non-coking coal deposits in India are characterized as high ash and difficult-to-wash coals. Quality improvement by beneficiation is almost mandatory due to MoEF notification to use <34% ash coal for all power plants except those located at pithead. Most of the coal washeries in India are based on wet process, where the coal fines are allowed to settle in thickeners. The coarser particles settle faster leaving the fine particles suspended for longer period. The dispersed fine coal particles contain some surface charge, which leads to the development of electrical repulsion between the particles, and as a result of this, the suspension becomes more stable. In order to destabilize the colloidal suspension, flocculants are usually added, so that the settling rate of the fine particles also increases. These flocculants are of cationic, anionic and non-anionic depending upon the type of charge released when dispersed in water. The flocculants may act partly for charge neutralization and partly for inter particle bridging and electrostatic patch formation. The effectiveness of any type of flocculants depends upon the molecular weight and charge density of the polymer. The paper discusses the settling behavior of non-coking coal fines suspension by using different flocculants. Keywords: floculent, coal fines, sedimentation rate, effluent

Sep 1, 2012

By S. H. Ash

THIS REPORT covers the third in a series of five projects into which the Conowingo tunnel system has been divided for geographical and practical reasons. It outlines the work constituting Project No.3 that consists principally of the following: (a) To sink the No. 15 shaft and extend the Alden, Sugar Notch, Baltimore No.2, and Laflin shafts from their present depths to tunnel level; (b) to drive a tunnel off these shafts to connect with the western end of the tunnel in Project No.1 (Lackawanna) and to a point 1 mile south of the No. 15 shaft; (c) to construct an emergency pumping plant at the No. 15 shaft, complete with 3 centrifugal pumps of 200-cubic-foot-per-second (c. f. s.) capacity each, and a discharge-water shaft and a discharge tunnel for conducting the water from the pumping plant into the Susquehanna River; and (d) to construct a lateral tunnel 1 mile long off the main tunnel in the vicinity of the No. 15 shaft, to be known as the Wyoming lateral. The project, as outlined, is a self-contained drainage unit that will permit unwatering inundated mines and safeguarding active mines in the Wyoming Basin of the Northern field and also will handle the water in the Lackawanna Basin, thus permitting the temporary pumping plant provided in Project No.1 to be discontinued. The pumps installed in the temporary pumping plant provided in Project No.1 can then be moved to the emergency pumping plants recommended in Projects Nos. 2 and 3, to be installed as the third or standby unit.

Jan 1, 1955

By S. H. Ash

THIS REPORT covers the second in a series of five projects into which the Conowingo tunnel system has been divided for geographical and practical reasons. It outlines the construction work contemplated-to sink two shafts on the line of the main tunnel that are designated the Nos. 9A and 11 shafts, to turn off from the No. 9A shaft the Lansford and Lykens laterals, and to drive portions of the main tunnel. An emergency pumping plant, consisting of 2 separate pumprooms, each containing 3 horizontal-type centrifugal pumps of 100,000-gallons-per-minute (g. p. m.) capacity, will be constructed at the No. 9A shaft. From the No. 11 shaft will be turned off the Trevorton lateral and portions of the main tunnel, which will connect with the section driven from the No. 9A shaft. Under the proposed project, the Lansford lateral will be driven for a distance of 2 miles, the Lykens lateral for a distance of 10.56 miles, and the Trevorton lateral for a distance of 20 miles. To drive the Lykens and Trevorton laterals for the distance indicated, several construction shafts and slopes must be sunk to permit efficient and safe construction.

Jan 1, 1955