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WO2018145146A1 - Compositions de biodiesel et leurs procédés d'utilisation - Google Patents

Compositions de biodiesel et leurs procédés d'utilisation Download PDF

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Publication number
WO2018145146A1
WO2018145146A1 PCT/AU2018/050073 AU2018050073W WO2018145146A1 WO 2018145146 A1 WO2018145146 A1 WO 2018145146A1 AU 2018050073 W AU2018050073 W AU 2018050073W WO 2018145146 A1 WO2018145146 A1 WO 2018145146A1
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WIPO (PCT)
Prior art keywords
biodiesel
methyl
particle
derived
flotation
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Application number
PCT/AU2018/050073
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English (en)
Inventor
Larissa KOROZNIKOVA
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Federation University Australia
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
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Publication date
Priority claimed from AU2017900381A external-priority patent/AU2017900381A0/en
Application filed by Federation University Australia filed Critical Federation University Australia
Publication of WO2018145146A1 publication Critical patent/WO2018145146A1/fr

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B03—SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
    • B03D—FLOTATION; DIFFERENTIAL SEDIMENTATION
    • B03D1/00—Flotation
    • B03D1/001—Flotation agents
    • B03D1/004—Organic compounds
    • B03D1/008—Organic compounds containing oxygen
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B03—SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
    • B03D—FLOTATION; DIFFERENTIAL SEDIMENTATION
    • B03D2201/00—Specified effects produced by the flotation agents
    • B03D2201/02—Collectors
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B03—SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
    • B03D—FLOTATION; DIFFERENTIAL SEDIMENTATION
    • B03D2203/00—Specified materials treated by the flotation agents; Specified applications
    • B03D2203/02—Ores
    • B03D2203/04—Non-sulfide ores
    • B03D2203/08—Coal ores, fly ash or soot

Definitions

  • the present invention is directed to the processing of mined materials including organic compounds (such as coal) and inorganic compounds (such as minerals).
  • mined materials including organic compounds (such as coal) and inorganic compounds (such as minerals).
  • the present invention is directed to biodiesel compositions and uses thereof in methods for separation and/or recovery of a mined material such as coal.
  • froth flotation In the processing of mined materials, it is often necessary to separate a subset of components from a mixture in a process stream.
  • the technique of froth flotation is often used for physically separating particles based on the differential abilities of the various particles in a process stream to adhere to air bubbles injected into a generally aqueous slurry. Particles which readily adhere to air bubbles are floated to the surface to form a froth phase, and are therefore partitioned away from the particles that remain completely wetted and remain in the lower slurry phase.
  • particles having hydrophobic characteristics are more likely to adhere to the air bubbles given their propensity to avoid water molecules.
  • Froth flotation is used in processing a broad range of mined materials, with a few examples being separation of fine coal particles from ash-forming minerals, separation of sulfide minerals from silica gangue and from other sulfide minerals; separation of potassium chloride from sodium chloride; separating silicate minerals from iron ores; and separating phosphate minerals from silicates.
  • Devising a froth flotation process is a complex undertaking, given the interplay between three major components: (i) equipment (including flotation cell design, agitation, and air flow), (ii) operation (including feed rate, particle size, pulp density and temperature), and (iii) chemistry (including collectors, frothers, activators, depressants and pH).
  • equipment including flotation cell design, agitation, and air flow
  • operation including feed rate, particle size, pulp density and temperature
  • chemistry including collectors, frothers, activators, depressants and pH.
  • Collectors are important agents in froth flotation, functioning to selectively adsorb onto the surfaces of particles in a flotation process.
  • the collector molecules form a thin hydrophobic film on the particle, which in turn increases the propensity for to the particle to adhere to a bubble.
  • Nonionic collectors can be generally classified according to their ionic charge: nonionic, anionic, or cationic.
  • Nonionic collectors are typically simple hydrocarbon oils, and similar compounds, that have an affinity for surfaces that already having hydrophobic properties. Nonionic collectors selectively adsorb on these surfaces, and increase their hydrophobicity.
  • the most commonly floated naturally-hydrophobic material is coal.
  • the use of collectors such as fuel oil and kerosene significantly and selectively increases the hydrophobicity of the coal particles largely without affecting the surfaces of associated ash-forming minerals. The floated coal particles are recovered to thereby improve the overall recovery of coal.
  • the present invention provides a method for floating a particle in the processing of a liquid mixture (such as a slurry or a pulp), the method comprising the steps of: contacting a liquid mixture having a plurality of particles with a biodiesel so as to form a particle-biodiesel complex, contacting the particle-biodiesel complex with a plurality of gas bubbles so as to form a particle-biodiesel-bubble complex, and floating the particle-biodiesel-bubble complex to the surface of the liquid mixture.
  • the biodiesel is derived from an oil feedstock.
  • the oil feedstock is plant-derived.
  • the oil feedstock is a vegetable oil.
  • the oil feedstock is derived from a plant of the family Asteraceae; optionally the subfamily: Helianthoideae; optionally the tribe Heliantheae; optionally the genus Helianthus, optionally the species H. annuus including any genetically modified variants thereof.
  • the oil feedstock is derived from a plant of the order Poaceae; optionally the genus Oryza, optionally the species: O. sativa or O. glabberrima including any genetically modified variants thereof.
  • the oil feedstock is derived from a plant having an oil containing less than about 2% erucic acid.
  • the oil feedstock is a canola oil.
  • the oil feedstock is derived from a plant of the order Brassicales; optionally the family Brassicaceae; optionally the geneus Brassica; optionally the species: B rapa or B napus or B juncea including any genetically modified variants thereof.
  • the oil feedstock in not animal-derived. In one embodiment of the first aspect, the oil feedstock is synthetic.
  • the biodiesel comprises a methyl ester having the formula: CH3-0-CO-R, wherein R is a hydrocarbon chain having a backbone of between 15 and 17 carbon atoms.
  • the methyl ester is selected from the group consisting of methyl palmitate, methyl stearate, cis-9-oleic acid methyl ester, methyl linoleate, and methyl linolenate.
  • the biodiesel comprises a combination of any two, three, four, or five of the following methyl esters: methyl palmitate, methyl stearate, cis-9-oleic acid methyl ester, methyl linoleate, methyl linolenate.
  • the biodiesel comprises methyl palmitate and/or methyl lineolate.
  • the biodiesel comprises methyl palmitate at a concentration of at least about 5% w/w of all esters contained in the biodiesel.
  • the biodiesel comprises methyl linoleate at a concentration of at least about 5% w/w of all esters contained in the biodiesel. In one embodiment of the first aspect, the biodiesel comprises methyl palmitate and methyl linoleate at a combined concentration of at least about 10% w/w of all esters contained in the biodiesel.
  • the method is devoid of the use of a petroleum-derived hydrocarbon as a collector in the formation of a particle-collector-bubble complex.
  • the particle is a coal particle. In one embodiment of the first aspect, the coal particle is in the size range of from about 50 ⁇ to about 500 ⁇ .
  • the method comprises the step of physically separating the floated particle from unfloated material in the liquid mixture.
  • the present invention provides the use of a biodiesel as a collector in the flotation of a particle in a froth floatation process.
  • the biodiesel is derived from an oil feedstock.
  • the oil feedstock is plant-derived.
  • the oil feedstock is a vegetable oil.
  • the oil feedstock is derived from a plant of the family Asteraceae; optionally the subfamily: Helianthoideae; optionally the tribe Heliantheae; optionally the genus Helianthus, optionally the species H. annuus including any genetically modified variants thereof.
  • the oil feedstock is derived from a plant of the order Poaceae; optionally the genus Oryza, optionally the species: O. sativa or O. glabberrima including any genetically modified variants thereof.
  • the oil feedstock is derived from a plant having an oil containing less than about 2% erucic acid.
  • the oil feedstock is a canola oil.
  • the oil feedstock is derived from a plant of the order Brassicales; optionally the family Brassicaceae; optionally the geneus Brassica; optionally the species: B rapa or B napus or B juncea including any genetically modified variants thereof.
  • the oil feedstock in not animal-derived. In one embodiment of the second aspect, the oil feedstock is synthetic.
  • the biodiesel comprises a methyl ester having the formula: CH3-0-CO-R, wherein R is a hydrocarbon chain having a backbone of between 15 and 17 carbon atoms.
  • the methyl ester is selected from the group consisting of methyl palmitate, methyl stearate, cis-9-oleic acid methyl ester, methyl linoleate, and methyl linolenate.
  • the biodiesel comprises a combination of any two, three, four, or five of the following methyl esters: methyl palmitate, methyl stearate, cis-9-oleic acid methyl ester, methyl linoleate, methyl linolenate.
  • the biodiesel comprises methyl palmitate and/or methyl lineolate.
  • the biodiesel comprises methyl palmitate at a concentration of at least about 5% w/w of all esters contained in the biodiesel.
  • the biodiesel comprises methyl linoleate at a concentration of at least about 5% w/w of all esters contained in the biodiesel. In one embodiment of the second aspect, the biodiesel comprises methyl palmitate and methyl linoleate at a combined concentration of at least about 10% w/w of all esters contained in the biodiesel.
  • FIGS. 1 A to ID are graphical representations of the composition of esters types in the various biodiesel compositions used in the coal floatation experiments described herein. The data represented in these figures are derived from Table 1.
  • FIG. 2A is a graphical representation of the results of comparative coal flotation experiments described herein showing the composition of coal recovered by flotation. The data represented in this figure is derived from Table 2. For each collector, the bars each represent (form left to right): carbon, ash, and volatiles.
  • FIG. 2B is a graphical representation of the results of comparative coal flotation experiments described herein showing the recovery of coal by flotation.
  • the data represented in this figure are derived from Table 2.
  • any one of the terms “comprising”, “comprised of or “which comprises” is an open term that means including at least the elements/features that follow, but not excluding others.
  • the term comprising, when used in the claims should not be interpreted as being limitative to the means or elements or steps listed thereafter.
  • the scope of the expression a method comprising step A and step B should not be limited to methods consisting only of methods A and B.
  • the present invention is predicated at least in part on Applicant's finding that biodiesels derived from oil feedstock, and particularly plant-derived oil feedstock are useful as collector agents in froth floatation applications. It has been discovered that esters derived from oil feedstock are effective substitutes for prior art collectors such as kerosene and fuel oil. In some cases, the biodiesels provide advantages over prior art collectors as further described herein.
  • the present invention provides a method for floating a particle in the processing of a liquid mixture (which is typically a slurry), the method comprising the steps of: contacting a liquid mixture having a plurality of particles with a biodiesel so as to form a particle-biodiesel complex, contacting the particle-biodiesel complex with a plurality of gas bubbles so as to form a particle-biodiesel-bubble complex, and floating the particle-biodiesel-bubble complex to the surface of the liquid mixture,
  • Particles for which the present methods are contemplated to applicable include any fine particles which a potentially floatable in a froth flotation method, and where the particles are floated with the assistance of a floatation agent which increases the hydrophobicity of the particle.
  • the methods are applicable to mining applications, including the processing of minerals (such as sulphides, carbonates, oxides and phosphates) and non- minerals such as coal.
  • the material to be treated may be reduced to fine particles by crushing and grinding so that the various minerals exist as physically discrete grains.
  • the particle sizes are typically less than 0.1 mm (100 ⁇ ).
  • the target of flotation is the existing fine coal particles and therefore crushing is not a required step.
  • the present methods may be applied to the cleaning of fine coal particles.
  • fine particles of coal are separated from other components in the mined material by the selective attachment of air bubbles to the particles causing them to be buoyed to the surface of a coal-water suspension where there are collected. Since non-coal particles (which are typically hydrophilic, and therefore do not effectively complex with a hydrophobic collector) remain unattached to the bubbles, they are not recovered in the froth.
  • This process cleans and separates the fine particles in a turbulent, aqueous environment where specific gravity is of lesser importance in the separation process as compared with the surface properties of the particles.
  • Froth floatation typically involves the thorough mixing of the fine coal particles with water. Frothers and other conditioning agents (including collectors) are added to the slurry and as air is bubbled up through the slurry the coal particles attach themselves to the bubbles and are carried to the surface. The resulting froth, containing primarily the hydrophobic components, is skimmed off, separating the coal from the mineral particles which remain in the water suspension.
  • the biodiesel used in the present methods may be any composition produced by the transesterification of lipids to produce fatty acid esters having 16-20 carbon atoms, 2 oxygen atoms and 28-38 hydrogen atoms.
  • Biodiesel can be manufactured from a vegetable oil, an animal fat or a waste oil, or indeed a combination of feedstock oils. Biodiesel may furthermore be manufactured synthetically, albeit the cost would likely render it uneconomic for the large scale industrial methods proposed herein.
  • Equation 1 Using methanol in the transesterification process has the advantage that the resulting glycerol can be separated simultaneously during the transesterification process.
  • the ethanol When using ethanol during the process the ethanol must be substantially free of water and the oil should have a low water content to achieve an easy glycerol separation.
  • the end products of the transesterification process are raw biodiesel and raw glycerol. After a cleaning step biodiesel is produced.
  • biodiesel is substantially non-toxic or at least less toxic than prior art collectors such as Kerosene.
  • Kerosene being a prior art collector
  • it has a low flash point 38°C and at ambient temperatures in a plant or in a storage facility may ignite or even explode.
  • biodiesel has a higher flashpoint (typically > 130°C).
  • this combination of low toxicity and higher flashpoint presents significant occupational health and safety issues.
  • biodiesel is biodegradable and does not present the disposal problems of kerosene and other petroleum-based collectors.
  • oil feedstock is intended to mean any feedstock which is a triglyceride and being in the liquid phase at 25°C.
  • the oil will typically be derived from a plant source; including but not limited to a plant seed, stem, leaf, root, vegetative structure, non-vegetative structure, reproductive structure, or fruit.
  • the use of oil feedstocks is generally preferable to the use of fat feedstocks. Fat feedstocks are typically obtained from animal-based materials such as beef tallow, pork lard and chicken fat. The use of animal fats as a feedstock is generally problematic.
  • Phospholipids may form insoluble insoluble precipitates when they come into contact with water, as required in a generally aqueous slurry in a froth floatation process. Such precipitates can co-partition with the floated coal particles in the froth phase, and should therefore be removed from the biodiesel before use in the present methods.
  • Polymers that are formed naturally at the high temperatures of the rendering process used in the conversion of animal fats to biodiesel can contribute to a higher viscosity in biodiesel.
  • the increase in viscosity that results can cause difficulty in dispersing the biodiesel in the aqueous slurry of the froth floatation cell.
  • a further problem with rendered fats of animal origin is polyethylene in the fat which comes from plastic bags, ear tags, or other plastic that is mixed with the animal byproducts. Finely divided polyethylene has been found to cause cloudiness in animals based biodiesel. These fine particles may co-partition with and contaminate the floated coal particles in the froth phase.
  • the high sulfur content of animal fat biodiesel may also confer an advantage in using oil- derived biodiesels.
  • the sulfur is thought to originate from sulfur-containing amino acids associated with proteins that carry over from the rendering process. The sulfur decreases by about one-half during the conversion to biodiesel, however significant amounts remain.
  • the presence of sulphurous compounds is generally undesired in coal products due to environmental concerns.
  • oils and particularly plant-based oils
  • biodiesel compositions in the present methods allows for the ability to use well defined and controlled biodiesel compositions in the present methods. It is proposed that the higher level of control will improve recoveries and the purity of the floated coal particles. Process issues will be lowered, and environmental issues lessened.
  • Methyl esters including methyl laurate, methyl myristate, methyl palmitate, methyl palmitoleate, methyl stearate, methyl oleate, methyl elaidate, methyl ricinoleate, methyl linoleate, methyl linolate, methyl arachidate, methyl gadoleate, methyl behenate, methyl erucate will be useful in coal floatation methods.
  • Applicant has shown empirically that useful recoveries of coal particles are found particularly with biodiesel having relatively high levels of methyl palmitate and/or methyl lineolate.
  • the biodiesel of the present method comprises methyl palmitate at a concentration of at least about 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40% and 45% (w/w) of all esters contained in the biodiesel.
  • the biodiesel of the present method comprises methyl lineolate at a concentration of at least about 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40% , 45% or 50% (w/w) of all esters contained in the biodiesel.
  • the biodiesel comprises methyl palmitate and methyl linoleate at a combined concentration of at least about 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, or 50% (w/w) of all esters contained in the biodiesel.
  • the plant from which the plant-derived feedstock may be derived may be any organism of the kingdom plantae.
  • the plant is one which is easily and economically cultivatable by commercial agriculture methods. More preferably, the plant is one which generates a reasonable amount of oil such as that found in palm, soybean, rapeseed, sunflower seed, peanut, cottonseed, palm kernel, coconut olive, ground nut with shell, maize, sesame seed, linseed, safflower seed, and soybean.
  • Other lesser-grown species such as Jatropha species, Camelina species (such as C. sativa), Acrocomia species (such as A. aculeata, Salicornia species (such as S.
  • Grasses may also be a useful and economic source of biofuel, including elephant grass, tall fescue, cock's foot, and canary reed grass.
  • Algae are a particular rich source of oil having a yield of around 95,000 litres per hectare (compared with around 6,000 litres per hectare for palm oil). Algae can be easy to grow, and does not require additional fertilizers or pesticides.
  • the algae can be grown in grey water or wastewater (in fact nitrogen-rich waste ponds are some of the better places to grow algae). It also can be grown on marginal land, does not therefore take away from land used in farming for food.
  • the following species are exemplary: Botryococcus braunii (20-42%); Neochloris oleoabundans (23%-40%), Nannochloropsis salina (37%), and Dunaliella tertiolecta (37%).
  • Botryococcus braunii (20-42%
  • Neochloris oleoabundans (23%-40%)
  • Nannochloropsis salina 37%
  • Dunaliella tertiolecta 37%
  • the algae is firstly dried before extraction of lipids for input into the transesterification process to produce biodiesel.
  • Nonionic collectors such as the biodiesel compositions described herein may be used as "extenders" for other collectors.
  • other collectors may be used as extenders in forth flotation methods using biodiesel as the primary collector.
  • the particles are rendered hydrophobic (or more hydrophobic), they are contacted with gas bubbles so that the bubbles can attach to the surface.
  • Contact between particles and bubbles is typically accomplished in a flotation cell whereby a rotor draws slurry through a stator and expels it to the sides, creating a suction that draws air down the shaft of the stator. The air is then dispersed as bubbles through the slurry, and comes in contact with particles in the slurry that is drawn through the stator.
  • Particle/bubble collision is affected by the relative sizes of the particles. If the bubbles are large relative to the particles, then fluid flowing around the bubbles can sweep the particles past and without coming in contact. It is therefore generally preferred that the bubble diameter is roughly comparable to the particle diameter in order to ensure useful particle/bubble contact.
  • Means for the collection of particles in the froth phase are also understood. Once a particle and bubble have come in contact, the bubble must be large enough for its buoyancy to lift the particle to the surface. This is easier if the particles are low density (as is the case for coal) than if they are high-density (such as lead sulfide). The particle and bubble must remain attached while they move up into the froth phase at the top of the cell.
  • the froth layer must persist long enough to either flow over the discharge lip of the cell by gravity, or to be removed by mechanical froth scrapers. If the froth is insufficiently stable, the bubbles will break and drop the hydrophobic particles back into the slurry prematurely. However, the froth should not be so stable as to become persistent foam, as a foam is difficult to convey and pump through the plant.
  • the surface area of the bubbles in the froth is also important. Since particles are carried into the froth by attachment to bubble surfaces, increasing amounts of bubble surface area allows a more rapid flotation rate of particles. At the same time, increased surface area also carries more water into the froth as the film between the bubbles. Since fine particles that are not attached to air bubbles will be unselectively carried into the froth along with the water (entrainment), excessive amounts of water in the froth can result in significant contamination of the product with gangue minerals.
  • the present methods may comprise the use of reagents other than collectors for certain applications.
  • frothers are compounds that act to stabilize air bubbles so that they will remain well-dispersed in the slurry, and will form a stable froth layer that can be removed before the bubbles burst.
  • the most commonly used frothers are alcohols, particularly MIBC (Methyl Isobutyl Carbinol, or 4-methyl-2-pentanol, a branched-chain aliphatic alcohol) or any of a number of water-soluble polymers based on propylene oxide (PO) such as polypropylene glycols.
  • the polypropylene glycols in particular are very versatile, and can be tailored to give a wide range of froth properties.
  • the PO and PO-Alcohol Adduct frothers are more powerful recovery agents than alcohol frothers, and therefore should be used at lower dosages. Over-dosing with alcohol frothers leads to a slower flotation rate, because excesses of these frothers tend to destabilize the froth. This effect does not occur with the PO and PO-Alcohol frothers, and so overdosing with these frothers leads to high recovery with poor selectivity. PO frothers with molecular weights of 300 to 500 are optimal for coal recovery.
  • Alcohol frothers tend to be more effective for fine-particle recovery than for coarse particle recovery.
  • the alcohol frother and the hydrocarbon collector dosages should both be high. The alcohol will still provide reasonable selectivity at these high dosages.
  • the high-molecular-weight PO-based frothers are more effective for coarse particle flotation than the alcohol or low-molecular-weight PO frothers, but also have a lower selectivity.
  • the PO frothers should be used at low dosage, with low collector dosage as well.
  • the PO-Alcohol Adduct frothers are even more effective for coarse-particle recovery, and need to be used at even lower dosages.
  • the total gangue recovered is linearly related to the total coal recovered. It is only for the finest particles that the gangue recovery increases non- linearly with increasing coal recovery. When floating coals with a broad particle size range, the majority of the gangue reaching the froth is from the finer particle size fractions.
  • the present methods may include the addition of a modifier.
  • Modifiers are chemicals that influence the way that collectors attach to particle surfaces. They may either increase the adsorption of collector onto a given particle (activators), or prevent collector from adsorbing onto a mineral (depressants).
  • the simplest modifiers are pH control chemicals.
  • the surface chemistry of most particles is affected by the pH.
  • the present may further include the use a modifier which is an activator.
  • Activators are specific compounds that make it possible for collectors to adsorb onto surfaces that they could not normally attach to.
  • Depressants may also be used. Depressants have the opposite effect of activators, by preventing collectors from adsorbing onto particular mineral surfaces. Their typical use is to increase selectivity by preventing one mineral from floating, while allowing another mineral to float unimpeded.
  • a floatation cell is a machine for mixing and dispersing air throughout the slurry while removing the froth product. Individual machines are connected to form a flotation circuit in order to fully clean the product.
  • Conventional flotation cells consist of a tank with an agitator designed to disperse air into the Slurry. These are relatively simple machines, with ample opportunity for particles to be carried into the froth along with the water making up the bubble films (entrainment), or for hydrophobic particles to break free from the froth and be removed along with the hydrophilic particles. It is therefore common for conventional flotation cells to be assembled in a multistage circuit, with "rougher”, “cleaner”, and “scavenger” cells, which can be arranged in various configurations.
  • Another type of equipment that may be used in relation to the present methods is a flotation column. Flotation columns provide a means for improving the effectiveness of froth flotation.
  • a column essentially performs as if it were a multistage flotation circuit arranged vertically, with slurry flowing downward while the air bubbles travel upward, producing a counter-current flow.
  • the basic principle of column flotation is the use of counter-current flow of air bubbles and solid particles. This is achieved by injecting air at the base of the column, and feed near the midpoint. The particles then sink through a rising swarm of air bubbles.
  • the collection zone is the volume where particle/bubble contact occurs, and it differs greatly in size between column and conventional flotation.
  • contact occurs primarily in the region surrounding the mechanical impeller.
  • the remainder of the cell acts mainly as a storage volume for material which has not yet been through the collection zone. This creates a bottleneck which keeps the flotation rate down.
  • flotation columns have a collection zone which fills the entire volume of the machine, so that there are more opportunities for particle/bubble collisions.
  • the reduced level of turbulence needed to achieve a good rate of recovery in columns also reduces the tendency of coarse particles to be torn away from the bubbles which they attach to, and therefore columns are more effective for floating coarser particles.
  • a second beneficial effect in certain types of flotation columns is the reduction of bubble diameter.
  • bubble diameter As bubble diameter is reduced, the flotation rate of both the coarser and finer particles is improved. Coarse particles can attach to more than one bubble if the bubbles are small, and therefore the chances of the particle being torn loose and sinking again is reduced.
  • the probability of collision with the bubble is improved if the bubble is small, as then the hydrodynamic forces tending to sweep the particle away from a collision are reduced.
  • the reduction of bubble diameter has the added benefit of increasing the available bubble surface area for the same amount of injected air. It is therefore desirable to produce bubbles as fine as possible.
  • the wash- water in the column cell displaces this feed water to the tailings, thus preventing entrained contaminants from reaching the froth.
  • the net effect of the relatively gentle mixing, counter-current flow, and use of wash-water in columns is that there is a distance of several meters between the clean coal discharging in the froth and the concentrated gangue discharging at the tailings, with a gradual gradient of concentration between the two extremes. There is therefore a reduced possibility of coal being misplaced into the tails, or of gangue short-circuiting to the froth.
  • the result is that a column is typically equivalent to between three and five stages of conventional flotation, depending on the column design.
  • a special bubble generator is typically provided in carrying out the present methods using floatation columns.
  • the impeller-type mixers that are used in conventional cells are not well- suited for use in flotation columns, as they would either need excessively long shafts or rotating seals.
  • bubbles were produced using sintered ceramic air diffusers which produced very fine air bubbles.
  • plugging problems particularly in hard water, and so cloth and perforated rubber sheeting were adopted instead.
  • the external bubble generators combine a stream of water with air to produce a mixture of very fine bubbles in water. This mixture is injected into the column.
  • This approach has a number of advantages, including: (1) The bubble generator is accessible for adjustment and maintenance; (2) There is no porous element inside the column to clog or become damaged, and so the dispersion of air in the column does not change; (3) The bubble generator can be designed to tolerate particulate matter in the water, and so recycle water can be used in the generators; and (4) External bubble generators can consistently produce very small bubbles in the column.
  • a key issue in flotation column operation is "axial mixing", which is mixing along the vertical axis of the column, as shown in Figure 16.
  • axial mixing is mixing along the vertical axis of the column, as shown in Figure 16.
  • the air bubbles rise in the column, they carry a portion of the water up with them to the base of the froth layer. The water then descends again, setting up a strong mixing action.
  • This tendency is greatest if the column is slightly tilted from vertical, as then the bubbles preferentially ascend on one side while the water descends on the other. This is why it is particularly crucial for flotation columns to be perfectly vertical.
  • the tendency towards axial mixing is also increased if some large bubbles are present, and so performance is best if the bubbles are uniformly small in diameter.
  • baffles made from perforated plates. These baffles interrupt the flow of the liquid as shown in Figure 16, preventing it from being rapidly carried to the surface, or from short circuiting directly to the tailings.
  • horizontal baffles in a flotation column have confirmed that they can greatly improve the operating characteristics of the column without sacrificing capacity, and a sufficiently open baffle design is highly resistant to plugging by coarse particles or debris.
  • flotation columns generally have superior performance to conventional flotation cells. However, they fundamentally require automatic control, as they are not well-suited for use of the simple tailings overflow weirs which are commonly used for maintaining a constant pulp level in conventional flotation cells.
  • release analysis which is carried out by progressively re-floating froth products to collect only the particles that are fully hydrophobic. Release analysis provides a means for comparing the performance of conventional flotation with column flotation. The product from release analysis is typically much higher-grade than the product from a single stage of conventional flotation. On the other hand, a correctly-operating flotation column will typically provide a product grade that is comparable to the grade of the product from the final stages of release analysis.
  • This model takes into account the fact that the hydrophobic particles vary in size and degree of hydrophobicity, and is therefore more appropriate than conventional reaction kinetics expressions that are intended to apply to systems of identical molecules. It is particularly useful for correlation of laboratory results with plant results.
  • the parameter R In conventional laboratory test work, it is common for the parameter R to be the most important in determining the flotation performance, because laboratory tests are often run until all floatable material is recovered.
  • the parameter K In the plant, it is common for the parameter K to be most important, because it is too expensive to provide enough cell volume to recover all material that does not float in a short time. Because of this difference in operation, the results of laboratory studies can be very poor predictors of plant performance.
  • Flotation cells for use in a plant must be selected based on laboratory and pilot-scale data. Laboratory tests are usually carried out as batch experiments and are generally quite straightforward, although it is necessary to keep a few points in mind: (a) The pulp must be agitated sufficiently to keep all particles in suspension; (b) It is often necessary to condition the reagents with the minerals for a period of time to ensure good coverage with collector; (c). In many cases, adding frother in stages along with makeup water may be necessary to keep the pulp level and froth depth constant; (d) The capacity of the cell increases as the percent solids increase, and so the best process economics are achieved at the highest percent solids practical. The most important information from this test work is:
  • Type of circuit Type of circuit, number cells per bank, number of flotation stages, and appropriate locations for recirculation of intermediate products.
  • the number of cells per bank depends on the flotation characteristics of the material being floated. Typical practice can be as low as 3 cells or as many as 17 cells per bank. In the case of coal, it is typical to utilize 4 to 6 cells, however in some circumstances only two cells may be used per bank.
  • the present invention will be now more fully described by reference to the following non- limiting examples.
  • biodiesel was made from four different oil feedstocks: vegetable oil, canola oil, sunflower oil and brown rice oil. Transesterification was carried out according to the Equation 1 herein.
  • the resultant biodiesel was washed with water to remove traces of KOH.
  • the biodiesel water mixture was made in a laboratory separation funnel and mixed well therein. The mixture was then allowed sufficient time to separate into its component parts, at which time the biodiesel fraction was taken. This washing process was repeated until the separated water fraction had a neutral pH and was clear to the naked eye.
  • the resultant biodiesel compositions were analysed for methyl ester content, with the results shown in Table 1 below:
  • Example 2 Comparative Coal Floatation Studies
  • biodiesel compositions as defined in Table 1 were used a collectors in the coal floatation process described above. As a comparator, kerosene was also assessed. All experiments were conducted using a single batch of fine black coal having particles sizes distributed in the range 75-500 ⁇ ). A slurry of 10% solids by mass was prepared by mixing the coal sample with water.
  • Methyl isobutyl carbinol was added to the slurry as a frother to an equivalent of 0.1 kg/t.
  • MIBC Methyl isobutyl carbinol
  • Each slurry sample was placed into a laboratory scale flotation cell having a capacity of 3.6 litres (EssaTM Flotation Test Machine, manufactured by FLSmidth Pty Limited, Australia)
  • the agitator of the floatation cell was turned on, and conditioning of the coal slurry/frother/collector mixture was allowed for 1 minute before the air valve was turned on to commence the injection of bubbles.
  • the recovered coal particles were dried, weighed and analysed.
  • FIG. 3 is a graphical representation of the recovery data presented for each collector in Table 3.
  • Recovery is calculated by reference to the amount of coal present in the feed that is recovered in the concentrate collected by floatation. A high recovery rate is highly desirable in coal floatation so as to minimise loss of coal in the tailings. It is noted that biodiesel derived from sunflower oil, rice oil and vegetable oil demonstrated better recoveries that than seen for kerosene under identical conditions. The best recovery was noted where biodiesel derived was rice bran oil was used as a collector.
  • biodiesel derived from rice bran oil demonstrated the highest proportion of methyl palmitate of all biodiesels tested. Given the biodiesel of rice bran oil demonstrated the highest recovery when used as a collector, it is proposed that the use of palm oils and other oils that will produce higher amounts of this methyl ester may produce even more effective biodiesel collectors for use in the present coal floatation method.
  • ester is methyl linoleate which is highest in biodiesel derived from sunflower oil and rice bran oil. Both biodiesels performed well as collectors, and so increasing the levels of this ester may provide improved recoveries of coals and decreased contaminant levels therein

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Abstract

La présente invention concerne le traitement de matériaux extraits comprenant du charbon. En particulier, mais pas exclusivement, la présente invention concerne des compositions de biodiesel et leurs utilisations dans des procédés de séparation et/ou de récupération de charbon. Selon un aspect, la présente invention concerne un procédé de flottation d'une particule de charbon dans le traitement d'un mélange liquide, le procédé comprenant les étapes consistant à : mettre en contact un mélange liquide ayant une pluralité de particules avec un biodiesel de façon à former un complexe particule-biodiesel, mettre en contact le complexe particule-biodiesel avec une pluralité de bulles de gaz de façon à former un complexe particule-biodiesel-bulle, et faire flotter le complexe particule-biodiesel-bulle à la surface du mélange liquide. Le biodiesel peut être dérivé d'une matière première d'origine végétale.
PCT/AU2018/050073 2017-02-08 2018-02-05 Compositions de biodiesel et leurs procédés d'utilisation WO2018145146A1 (fr)

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WO2024048220A1 (fr) * 2022-08-31 2024-03-07 三菱化工機株式会社 Système de mélange de mazout et procédé de mélange de mazout
WO2024112673A1 (fr) * 2022-11-21 2024-05-30 Phinix, LLC Nouveau procédé et chimie de flottation pour récupération de métaux de valeur à partir de cendres d'incinération de déchets solides municipaux (mswi)
JP7681810B2 (ja) 2022-08-31 2025-05-22 三菱化工機株式会社 燃料油混合システム及び燃料油混合方法

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2024048220A1 (fr) * 2022-08-31 2024-03-07 三菱化工機株式会社 Système de mélange de mazout et procédé de mélange de mazout
JP7681810B2 (ja) 2022-08-31 2025-05-22 三菱化工機株式会社 燃料油混合システム及び燃料油混合方法
WO2024112673A1 (fr) * 2022-11-21 2024-05-30 Phinix, LLC Nouveau procédé et chimie de flottation pour récupération de métaux de valeur à partir de cendres d'incinération de déchets solides municipaux (mswi)

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