ES2335384T3 - PROCEDURE FOR THE USE OF NATURAL PRODUCTS AS DEHYDRATION ASSISTANTS FOR FINE PARTICLES. - Google Patents

Abstract

A new method of improving the process of dewatering fine particulate materials is disclosed. In this method, an aqueous slurry of fine particles is treated with appropriate hydrophobizing reagents so that the particulate material becomes moderately hydrophobic. A lipid of vegetable or animal origin is then added to the slurry in solutions of light hydrocarbon oils and short-chain alcohols, so that the hydrophobic lipid molecules adsorb on the moderately hydrophobic surface and, thereby, greatly enhance its hydrophobicity. By virtue of the enhanced hydrophobicity, the water molecules adhering to the surface are destabilized and more readily removed during the process of mechanical dewatering. The moisture reduction can be further improved using appropriate electrolytes in conjunction with the lipids, spraying surface tension lowering reagents onto the filter cake, subjecting the cake to a suitable vibratory means, and using combinations thereof.

Description

Procedure for using natural products such as dehydration adjuvants for fine particles.

Background

Many particulate materials are produced and processed in aqueous media. Before being sold to customers or from be processed further, it is often necessary to remove Water. Dehydration can be achieved well by means mechanical (for example, filtration and centrifugation) or by thermal drying In general, the former are cheaper than the latest. However, mechanical dehydration becomes inefficient. with finer particles. Dehydrated products contain high humidity and often require thermal drying to meet the specifications.

In a mechanical dehydration procedure determined, most of the water is quite removed quickly. What is difficult to remove is the water that adheres to the surface of the particulate material. In this way, the amount of wastewater left in the product is approximately proportional to its surface area. For a given material, the area specific surface is inversely proportional to the square of its particle size Therefore, the residual humidity in the filtered products increase, therefore, with the decreasing particle size. A more quantitative explanation. for the difficulty in dehydration of fine particles by filtration can be provided by the equation of Laplace:

one

where Δp is the pressure of the water inside a capillary (formed between the particles present in a filter cake), r is the radius of the capillary, γ is the surface tension of the water and \ is the contact angle of the particles in the cake. The contact angle is a measure of the hydrophobicity (water repulsion property) of the particles. Ec. [1] shows that the pressure required to expel the water from the capillary increases with the decreasing capillary radius. Whereas the finer particles form smaller capillaries, the difficulty of dehydrating fine particles can be seen. With a given filter cake, consisting of particles of different sizes, there must be a distribution of capillaries of several radii. At a given pressure drop applied through a filter cake, it would be difficult to expel water from capillaries whose radii are less than a certain critical value. In this way, the number of capillaries, whose radii are less than the critical radius, should determine the final humidity of the cake.

Several polymeric flocculants are used to increase the particle size and, therefore, to minimize the number of smaller capillaries. Coagulants can also be used. electrolytic to increase particles. Groppo and Parekh (Coal Preparation, 1996, vol. 17, pp. 103-116) showed that dehydration of fine coal improves considerably in presence of divalent or trivalent cations. They found this happens when cationic, anionic and non-surfactants are used anionic

Eq. [1] also suggests that the pressure capillary should be reduced with a decreasing surface tension and An increasing contact angle. Several surfactants are used to Reduce surface tension. Most adjuvants of Dehydration used for this purpose are ionic surfactants with hydrophilic-lipophilic balance numbers (HLB) high. Sodium lauryl sulfate and dioctyl sulphosuccinate sodium, whose HLB numbers are 40 and 35.3, respectively, are typical examples. Singh (Filtration and Separation, March, 1977, pp.  159-163) suggests that the former is an adjuvant of ideal dehydration for coal because it is not absorbed in the surface, which in turn allows reagents to be fully used to reduce surface tension. The U.S. patent No. 5,346,630 teaches a spray procedure under pressure of a solution of a dehydration adjuvant from a position within the filter cake formation zone of a filter, just before the disappearance of the supernatant water of process. This procedure, which is called the system of torpedo spraying, ensures a homogeneous distribution of dehydration adjuvant without being diluted considerably by the supernatant water of the process.

It is well known that HLB surfactants high can actually cause an increase in humidity in the dehydration of hydrophobic materials, such as coal. Due to the high polarity of their head groups, the High HLB surfactants are absorbed on hydrophobic surfaces with inverse orientation, that is, with the hydrocarbon tails in contact with the surface and polar heads pointing towards the aqueous phase. Such absorption mechanism should reduce the hydrophobicity, and therefore, should cause an increase in cake moisture. Most of the flocculants used as dehydration adjuvants also buffer hydrophobicity and They cause an increase in humidity.

There are several U.S. patents. that they disclosed procedures for using low HLB surfactants as adjuvants dehydration U.S. patents Nos. 4,447,344 and 4,410,431 disclosed procedures for using non-ionic surfactants Water insoluble with their HLB numbers in the range of 6 to 12. These reagents were used together with reagents (hydrotropes) that they are able to keep the surfactants in solution or in the air-water interface instead of on the interface solid-liquid, so that they can be used entirely to reduce surface tension. The advantage of using low HLB surfactants may be that, unlike High HLB surfactants do not have the detrimental effects of hydrophobicity damping.

U.S. Patent No. 5,670,056 teaches a method of use of polymers and non-ionic surfactants of HLB low as hydrophobicizing agents that can increase the angle of contact above 65º and, in this way, reduce humidity of the cake. Monounsaturated fatty esters, fatty esters whose HLB numbers are less than 10, and the Water soluble polymethylhydrosiloxanes were used as agents hydrophobicizers Fatty esters were used with or without use of butanol as a carrier solvent for HLB surfactants low. The disclosure of the present invention lists a group of particulate materials that can be dehydrated using these reagents These include, coals, clays, sulphide minerals, phosphates, metal oxide minerals, industrial minerals and waste materials, most of which are hydrophilic. He use of HLB surfactants under disclosed in U.S. Pat. Do not. 5,670,056 may be able to increase the contact angles of materials that are already hydrophobic but not for particles hydrophilic

U.S. Patent No. 2,864,765 teaches a method of using polyoxyethylene other than an ester of Partial long chain fatty acid hexitol anhydride, which It works alone or as a solution in kerosene. However, the disclosure does not mention that the nonionic surfactant increases the hydrophobicity of moderately hydrophobic particles. Further, the disclosed compounds are not essentially absorbed in the solid surface of the mineral particles and remain in the filtered, as indicated in U.S. Pat. No. 4,156,649. In this last patent and also in U.S. Pat. No. 4,191,655, it disclose procedures for the use of alkylethoxylated alcohols linear or branched, as dehydration adjuvants. Were used in hydrocarbon solvent solutions but in presence of water soluble emulsifiers, such as dioctyl sulphosuccinate sodium. As stated previously, the use of said high HLB surfactant can cushion hydrophobicity and cause an increase in humidity.

U.S. Patent No. 5,048,199 disclosed a method of using a mixture of a non-ionic surfactant, a sulfosuccinate and a deforming agent. U.S. Patent No. 4,039,466 disclosed a method of using a surfactant combination nonionic having a polyoxyalkylene group and a surfactant anionic U.S. Patent No. 5,215,669 teaches a procedure of use of water soluble mixed hydroxyether, which is supposed to works well with both hydrophobic materials (carbon) and with hydrophilic materials (wastewater). U.S. Patent Do not. 5,167,831 teaches surfactant use procedures non-ionic with HLB numbers from 10 to 14. This procedure is useful for dehydrating alumina trihydrate made by the Bayer procedure, which is hydrophilic. The U.S. patent No. 5,011,612 disclosed acid use procedures C 8 to C 20 fatty acids, fatty acid precursors, such as esters or amides, or a mixture of fatty acids. Again these Reagents are designed to dehydrate alumina trihydrate hydrophilic

U.S. Patent No. 4,206,063 teaches procedures for using polyethylene glycol ether of a linear glycol with its HLB number in the range of 10 to 15 and an alcohol ethoxylate linear primary that contains 12 to 13 carbon atoms in the alkyl fraction. These reagents were used to dehydrate mineral concentrates in conjunction with hydrophobic alcohols that They contained 6 to 24 carbon atoms. The composition of this invention was preferably used in conjunction with flocculants polymeric Similarly, U.S. Pat. No. 4,207,186 disclosed methods of using a hydrophobic alcochol and a non-ionic surfactant whose HLB number was in the range of 10 to 15.

It is well known that oils can improve the hydrophobicity of coal, this being the reason why various mineral oils are used as flotation manifolds of Coal. U.S. Patent No. 4,210,531 teaches a procedure of dehydration of mineral concentrates using a flocculant polymeric, followed by a combination of an anionic surfactant and an organic liquid insoluble in water. The use of flocculant and Ionic surfactants can be beneficial in dehydration, but could dampen the hydrophobicity of the particles and, of In this way, they could adversely affect the procedure. The U.S. patent No. 5,256,169 teaches to treat an aqueous suspension of fine coal with an emulsifiable oil in combination with a elastomeric polymer and an anionic and non-ionic surfactant, dehydrate the aqueous suspension and dry the cake from the filtrate, where the oil reduces the spread of fugitive dusts. The U.S. patent No. 5,405,554 teaches a procedure of dehydration of municipal waste, which is not hydrophobic, using water-in-oil emulsions stabilized by cationic polymers. U.S. Patent Do not. 5,379,902 disclosed a procedure for using heavy oils in conjunction with two different types of surfactants, subjecting flotation the carbon-emulsion mixture, dehydrating the floating product and drying it for reconstitution. The patent U.S. No. 4,969,928 also teaches a procedure for using heavy oils for dehydration and reconstitution.

U.S. Patent No. 4,770,766 disclosed procedures to increase the hydrophobicity of coals oxidized and low range using additives during agglomeration of oil. The main objective of this procedure is to improve agglomeration kinetics and ultimately the separation of the hydrophilic mineral matter of coal. The additives disclosed in This invention includes a variety of heavy oils and oils vegetables, alcohols containing 6 or more carbon atoms, long chain fatty acids, etc. When were these used? additives, the humidity of the product was lower than it would be in Other circumstances However, the procedure requires up to 150 kg / t (300 lb / ton) of additives and use very large quantities (45 to 55% by volume of a carbon to be clarified) from a binder, which is selected from butane, hexane, pentane and heptane.

U.S. Patent No. 5,458,786 disclosed a fine coal dehydration procedure displacing water of the surface with a large amount of liquid butane. Butane Used is recovered and recycled. U.S. Patent No. 5,587,786 teaches procedures for using liquid butane and other liquids hydrophobic to dehydrate other hydrophobic particles.

Objects of the invention

It is an object of the present invention provide new moisture reduction procedures of fine particulate materials during mechanical procedures dehydration, such as centrifugation and pressure filtration or vacuum filtration.

Another important object of the invention is the provision of an improvement in the rate at which water is removed, so that a given dehydration team can process higher tonnages of particulate materials.

A further object of the present invention is the provision of new dehydration procedures for fine particles that can reduce moisture so much, other than thermal drying necessary.

Still another object of the present invention is the provision of a new dehydration procedure that does not create adverse effects on upstream and downstream procedures below, when the water removed from the procedures dehydration disclosed in the present invention be recycled

Still another object of the invention is the provision of foaming properties control procedures  of the flotation product.

Perhaps the most important object of the present invention is to get all the objects indicated above using dehydration adjuvants that can be achieved at low cost and have no harmful effects on the environment and on the Human health.

Summary of the Invention

It is the object of the present invention provide a material dehydration procedure Fine fine particulates. This is achieved by destabilizing the water on the surface of the particles to dehydrate, turning the surface in substantially hydrophobic. The particles are hydrophobicized in two stages. Initially, surfactants are used, preferably with balance numbers high hydrophilic-lipophilic (HLB), or collectors, for convert a particulate material into moderately hydrophobic. He material is subsequently treated with a lipid, which is a natural hydrophobic substance, to further improve its hydrophobicity up to a value close to or greater than the angle of 90º water contact. This will considerably weaken the links between water molecules and the surface of the material particulate and, in this way, "releases" the water from the surface. Next, the surface water released is removal of particulate material using various devices mechanical dehydrators

The key to dehydration procedures described in the disclosure of the present invention is the step of Improvement of hydrophobicity. According to the Laplace equation, a relatively small increase in hydrophobicity (over level that can normally be achieved using an HLB surfactant high in the first stage of hydrophobicization) can cause a large reduction in capillary pressure and, in this way, a Great reduction in surface moisture.

The lipids used in the second stage of hydrophobicization of the present invention are water insoluble; therefore, they are used as solutions in appropriate solvents, that include but are not limited to, light hydrocarbon oils and short chain alcohols. When used in conjunction with a Appropriate solvent, lipid molecules can act as nonionic surfactants that can significantly improve the hydrophobicity of the particulate material to be dehydrated. Because lipids are natural reagents, their use offers a medium of low cost to improve the mechanical procedures of dehydration

Dehydration procedures in the The present invention is not only able to reduce the humidity of the final cake, but they can also increase substantially the kinetics of dehydration. Under the latter, the The present invention can greatly increase the performance of a dehydration device. In addition, the dehydration adjuvants of the present invention have characteristics of anti-formation agents, which It is very important to process particulate materials produced at Starting from flotation procedures. Also, most of the reagents added as dehydration adjuvants and mixtures thereof, they are absorbed on the surfaces of minerals and coal, of so that the plant water does not contain quantities considerable residual reagents.

Detailed description of the invention

The difficulty of removing water from the Fine particle surface can be attributed to the fact that the water molecules are strongly attached to the surface by hydrogen bonds It is possible to break the links and remove the water subjecting the wet particles to intense heat, filters high pressure and high G centrifuges. However, the use of such brute forces implies high energy costs and problems of maintenance. A better solution would be to destabilize water from the surface by appropriate chemical means, so that can be more easily removed using devices mechanical dehydration with maintenance requirements and minimum energy

The state of water adhered to a surface can be represented in the best way by hydrophobicity  (water repulsion property). The older the hydrophobicity, weaker are the links between water and the surface. Therefore, the key to finding the means Appropriate chemicals to destabilize surface water is increase the hydrophobicity of the particles to be dehydrated. A more traditional measure of the hydrophobicity of a surface is the water contact angle. In the technique of sessile gout, the contact angles are measured by placing water drops on the surface of the solids of interest. The contact angle, which measured through the aqueous phase, increases by increasing the hydrophobicity

More recently, scientists have developed procedures for measuring forces between two macroscopic surfaces approaching each other in water. They discovered an attractive force unknown until now, which is generally called hydrophobic force. Many researchers showed that the new attractive force is 10 to 100 times stronger than the omnipresent force of van der Waals. Yoon and Ravishankar (J. Colloid and Interface Science, vol. 179, p. 391, 1996) showed that the hydrophobic force increases sharply when the contact angles of two interacting mica surfaces approach 90 °. According to Eq. [1], the capillary pressure becomes negative at contact angles greater than this value. Thus, if the hydrophobicity of a particulate material could be increased to a point where its contact angle exceeds 90 °, the water should be removed spontaneously. This can be achieved using appropriate surfactants. According to Flinn et al . (Colloids and Surfaces A, vol. 87, p. 163, 1994), the hydrocarbon tails of octadecylchlorosilane begin to be placed vertically and form a compact monolayer on the silica surface at a contact angle close to or greater than 90 °. Also, Yoon and Ravishankar observed long-range hydrophobic forces only when compact monolayers formed on mica surfaces. Therefore, it seems that the key to achieving spontaneous dehydration may be to find appropriate surfactants or combinations thereof that can form compact monolayers of hydrophobes on the surfaces of the particles to be dehydrated.

In the present invention, the materials particulates in an aqueous suspension are hydrophobicized in two stages In the first stage, a collector or surfactant is added appropriate to the aqueous suspension, so that it can be absorbed on the surface of the particles and do them moderately hydrophobic For hydrophilic particles, such as silica and clay, high HLB surfactants can be used for initial hydrophobicization. For sulphured minerals, they can Use short chain thiols. These reagents are absorbed in the surface with its polar heads in contact with the surface and its hydrocarbon tails directed towards the aqueous phase. For the natural hydrophobic materials of moderate hydrophobicity, can used hydrocarbon oils and short chain alcohols for improve hydrophobicity In the second stage, a dissolved lipid in a suitable solvent or in a mixture of solvents it is added to the aqueous suspension to further increase hydrophobicity of particulate materials, so that the water in the surface can be more easily removed by mechanical procedures of low consumption dehydration of Energy.

As a result of the first stage of hydrophobicization, the contact angle of the particulate material at dehydration is increased at the interval of 25º to 60º. It's hard, but not impossible, get contact angles greater than this interval using only a high HLB surfactant. The thiols and High HLB surfactants are absorbed only at surface sites specific. The population of surface sites, in which absorption can occur, it is usually well below which is necessary to form a compact monolayer of molecules absorbed surfactants. Reagents added in the second stage hydrophobicization, that is, lipids dissolved in solvents appropriate, can be absorbed between the hydrocarbon tails sparsely populated with thiols and high HLB surfactants, so that the surface is more completely covered by a compact monolayer of hydrophobes. This will increase the angle of contact over 60 ° and more desirably close to 90 ° or over 90 °, of so that water can be easily removed from the capillaries formed between the finest particles.

Although the Laplace equation suggests that the contact angle must exceed 90º for dehydration spontaneous, increasing contact angles near this value, but without exceeding it, can cause sufficient advantages. A close examination of Eq. [1] reveals that an increase in angle of higher contact than can be achieved in the first stage hydrophobicization can cause a substantial reduction in the capillary pressure and, therefore, a reduction in the humidity of the cake. Consider a case where the contact angle is increased from zero to 60º in the first hydrophobicization stage. This should reduce capillary pressure only in half. If he angle is further increased from 60º to 85º in the second hydrophobicization stage, capillary pressure is reduced additionally in 5.7 times. This is a substantial gain that can be achieved by a seemingly modest increase in The contact angle. In this way, the second stage of hydrophobicization disclosed in the present invention offers a means highly efficient of substantially reducing pressures capillaries and, in this way, to get very wet cake low.

Lipids are natural organic molecules that can be isolated from cells (and tissues) from plants and animals by extraction with organic solvents not polar. Much of the molecules are hydrocarbons (or hydrophobic), therefore, are insoluble in water but soluble in organic solvents, such as ether, chloroform, benzene or a alkane In this way, the definition of lipids is based on the physical property (i.e. hydrophobicity and solubility) instead of in the chemical structure or composition. Lipids include a wide variety of molecules of different structures, that is, triacylglycerols, steroids, waxes, phospholipids, sphingolipids, terpenes and carboxylic acids. They can be found in various oils vegetables (for example, soybean oil, peanut oil, oil olive, linseed oil, sesame oil), fish oil, butter and tallow. Animal fats and vegetable oils are the lipids that occur most frequently. Although fats and oils seem to be different, that is, the first ones are solid and the latter are liquid at room temperature, their structures They are closely related. Chemically, both are triacylglycerols; that is, glycerol triesters with three acids long chain carboxylic. They can be easily hydrolyzed in fatty acids. Corn oil, for example, can be hydrolyzed  to obtain mixtures of fatty acids, consisting of 35% acid oleic, 45% linoleic acid and 10% palmitic acid. The olive oil hydrolysis products, on the other hand, They consist of 80% oleic acid. Waxes can also be hydrolyzed, while steroids are not. The oils and Vegetable fats are normally produced by expression and solvent extraction or a combination of the two. The pentane is widely used as a solvent, and is capable of extracting 98% of soy oil. Some of the impurities present in the oil crude, such as fatty acids and phospholipids, are removed from the raw vegetable oils by precipitation and refined by alkali. Animal oils are normally produced by melting fat

In the present invention, lipids can act as natural surfactants that can improve the hydrophobicity of the particles to be dehydrated. Every triacylglycerol, for example, consists of a head group, it is ie, glycerol, and three hydrocarbon tails. For steroids, hydroxyl groups can act as polar heads while ester bonds serve as head groups with waxes. They can act effectively as non-ionic surfactants of numbers Low hydrophilic-lipophilic balance (LBH). The HLB numbers of soybean oil and corn oil are 6 and 8, respectively, while that of castor oil is 14. They can be absorbed between or at the top of the chains of hydrocarbons of the surfactants and thiols that are present in the surface of the fine particles as a result of the first hydrophobicization stage and therefore improve the hydrophobicity

Because lipids have HLB numbers low, can be used as appropriate solvent solutions including, but not limited to, short chain alcohols and light hydrocarbon oils. Typically, a part by volume of a lipid, which can be referred to as an active ingredient or active ingredients, dissolved in two parts of a solvent before use. The two can be mixed in relationships different. As an example, three parts of an active ingredient They can be mixed with a part of a solvent. In another example, one part of an active ingredient can be mixed with 20 parts of a solvent.

For example, mineral constituents (or carbon) selected from a mineral (or coal) are hydrophobicized selectively using appropriate reagents (e.g., High HLB surfactants, thiols, light hydrocarbon oils and short chain alcohols) and are separated by flotation of hydrophilic mineral constituents as a means of separation and empowerment. The particulate material to be dehydrated must be moderately hydrophobic so that the second stage of Hydrophobicization disclosed in the present invention works. Of what on the contrary, the hydrophobic lipids disclosed cannot be absorbed on the surface by hydrophobic attraction and improve its hydrophobicity Frequently, hydrophobic materials natural or mineral concentrates become considerably less hydrophobic when they reach the dehydration stage, due to to surface oxidation, aging, or exposure to water from plant containing hydrophilic polymers. In these cases, they can be re-hydrophobicized using HLB surfactants high and other reagents indicated above before adding the reagents identified in the present invention for the second hydrophobicization stage.

It may be useful to indicate here that the concentrates of coal and minerals obtained by flotation are not hydrophobic enough to be efficiently dehydrated. The reason is that the thermodynamic requirement for adhesion bubble-particle, which is a prerequisite for flotation, is that the angle of contact is greater than zero, while the requirement Thermodynamic for spontaneous dehydration is 90º, as It has been indicated above. Therefore, the second stage of Hydrophobicization is essential to reduce cake moisture more beyond the levels that are normally achieved using the procedures and dehydration adjuvants available in the present. The use of lipids in the second stage of hydrophobicization provides a low cost means to increase the contact angle near or above 90º.

For a particular particulate material, parts of the surface should be more hydrophobic than the rest. When use a lipid as a dehydration adjuvant, most of the molecules can be absorbed in the most hydrophobic parts of the surface, thus increasing the density of surface hydrophobic packaging and increasing additionally its hydrophobicity. The driving force for the Absorption mechanism can be one of hydrophobic attraction. By On the other hand, some of the lipid molecules can be absorbed in less hydrophobic parts of the surface, with the oxygen in the head groups in contact with the less parts surface hydrophobic, possibly through interactions acid-base while hydrocarbon tails They point to the aqueous phase. The net result of this mechanism of absorption would be a conversion of the less hydrophobic parts of a surface in more hydrophobic ones. Both types of mechanisms, that is, one based on the hydrophobic interaction and the other based on acid-base interactions should help substantially increase surface hydrophobicity, approaching its contact angle at 90º, or exceeding 90º.

Light hydrocarbon oils used as Solvents for lipids can also be absorbed in the surface of the particulate material to be dehydrated by hydrophobic interaction, and further improve its hydrophobicity. Indeed, lipid molecules can act as non-surfactants. ionic and can help propagate hydrocarbon oils light on the surface modifying interfacial tensions involved Lipid molecules should increase tension interfacial in the solid / water interface, as a result of doing the more hydrophobic surface, causing at the same time a reduction of the interfacial tensions in the oil / water interfaces and solid / oil The improved spread of hydrocarbon oil Lightweight should contribute to improve the hydrophobicity of the surface up to about 90º or more than 90º. In addition, all reagents used in the present invention can also serve as surface tension reducing agents. Tensions surface lipids, hydrocarbon oils and alcohols Short chain are substantially inferior to water. its presence in the air-water interface, by virtue of its hydrophobicity, should reduce surface tension and, of this way, help reduce cake moisture according to the equation from Laplace.

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Test procedure

Many different samples were used for dehydration tests. These included fine silica, clay Central Georgia kaolin (60% thinner than 2 µm), several carbon samples from different sources and mineral concentrates sulfurized A hydrophilic material, such as silica and kaolin, was hydrophobicized in two stages: first using an HLB surfactant high to make the surface moderately hydrophobic and, to then using a lipid to further improve your hydrophobicity Because lipids are insoluble in water, these were used after dissolution in suitable solvents. When sulphide mineral concentrates were received from abroad, these oxidized superficially and became in hydrophilic As a means of regenerating surfaces fresh hydrophobes, were re-floated using a thiol collector and methyl isobutyl carbinol (MIBC) as a foaming agent. This was necessary because lipids are not absorbed in hydrophilic surfaces

Some of the carbon samples were used as received. Most of the trials were performed,  however, after a re-flotation using standard flotation reagents, such as kerosene and MIBC. When a sample became hydrophilic due to aging or surface oxidation during transport, it was wet milled in a ball mill for a short period of time to remove the oxidation products and regenerate the fresh, moderately hydrophilic surfaces. Lipids are they absorb on the surface and improve their hydrophobicity. For minimize problems concerning oxidation, some of the tests were performed using rough medium dense products. They were crushed, pulverized, wet ground in a mill balls, and subjected to flotation using kerosene and MIBC. The product Under flotation it was placed in a container and stirred. A known volume of the aqueous suspension was removed and transferred to an Elenmeyer flask. After adding quantities known reagent or reagents, the flask was shaken by hand for 2 minutes The conditioned aqueous suspension was poured into a filter to start a dehydration test. After a default drying cycle time (usually 2 minutes), the product was removed from the filter, dried in an oven during night, and then it was heavy to determine the humidity of the cake. In each trial, the formation time of the cake and the thickness of the cake. Cake formation time It is defined as the time needed for most of the water Drain and form a cake in a filter medium. For one vacuum filtration, a 6.35 cm Buchner funnel was used (2.5 inches) in diameter with a porous glass porous filter half. When you wanted to perform the cake thickness tests large, the height of the Buchner filter was extended. For filtering under pressure, a 6.35 cm (2.5 pressure air filter) was used inches) in diameter with a medium of cloth. It was done in Plexiglas, so that the cake formation time could Be determined by visual observation.

Examples Example 1

A sample of fine silica from Tennessee was wet milled in a ball mill and was sifted to obtain a fraction of 0.074 mm x 0. It was subjected to two sets of vacuum filtration tests, using varying amounts of a lipid (sunflower oil) with and without the first stage of hydrophobicization Dodecylammonium hydrochloride was used in the 0.2 kg / t (0.4 lb / ton) at pH 9.5 for hydrophobicization initial. Sunflower oil was used as a 33.3% solution in diesel All trials were performed using a funnel. Buchner 6.35 cm (2.5 inches) in diameter to 1.143 cm (0.45 inches) of cake thickness, 2 minutes of cycle time drying and a vacuum pressure of 635 mm (25 inches) of Hg.

The control test performed without any reagent provided 21.2% by weight of cake moisture and 104 seconds of cake formation time, as shown in Table 1. When the tests were performed using oil Sunflower without the initial hydrophobicization stage, both moisture as the cake formation time was reduced only slightly. These findings suggest that lipids are not they absorb on the surface of hydrophilic silica and, therefore, do not They can work as efficient dehydration adjuvants. When the tests were performed after the stage of initial hydrophobicization but without the second stage of hydrophobicization, the humidity of the cake was reduced to 15.3% and the cake formation time to 21 seconds.

When the silica sample was hydrophobicized in Two stages, as disclosed in the present invention, are they got substantial reductions in cake moisture. By example, the procedure that involves a hydrophobicization stage initial using 0.2 kg / t (0.4 lb / ton) of a high HLB surfactant (dodecylammonium hydrochloride) and an improvement stage of hydrophobicity using 1 kg / t (2 lb / ton) of sunflower oil reduced the humidity of the cake from 21.2% to 6.2% and the formation of the cake of 104 seconds to 11 seconds.

TABLE 1 Effects of the use of sunflower oil as an adjuvant dehydration for filtration of a sample of 0.074 mm x 0 silica at a vacuum pressure of 635 mm (25 inches) of Hg

2

The tests were also performed with a finest silica sample (0.034 mm X 0). A control test provided a cake moisture of 26.4% and a formation time of the cake of 161 seconds. With a procedure of single stage hydrophobicization using 0.2 kg / t (0.4 lb / ton) of dodecylammonium chloride at pH 9.5, cake moisture was reduced to 19.2% and the cake formation time to 26 seconds. With the two-stage hydrophobicization procedure using 0.2 kg / t (0.4 lb / ton) of the HLB surfactant high in the first stage and 1 kg / t (2 lb / ton) of a lipid (sunflower oil) in the second stage, the Cake moisture was substantially reduced to 8.9% and the time of cake formation at 11 seconds.

Example 2

The high gloss kaolin clays are produced by reverse flotation, that is, impurities colored are hydrophobicized by appropriate collectors and are separated by floating the clay that remains hydrophilic. Normally, the product is in the form of 25 to 35% solids, and is dehydrated by vacuum filtration to obtain a cake that It contains a humidity of 50-55%. Cake part of The filtrate is thermally dried and then mixed with the remaining wet cake to further reduce moisture to a 25-30% range. In this example, a series of filtration tests on a kaolin clay from central Georgia (60% finer than 2 µm) to show that the procedure of dehydration, as described in the disclosure of the present invention, you can dehydrate the clay by filtration  under vacuum at a desired level without thermal drying. All rehearsals were performed using a 6.35 cm (2.5 cm Buchner funnel) inches) in diameter at 635 mm (25 inches) Hg, 0.41 cm (0.16 inches) of cake thickness and 3 minutes of cycle time dried

When the trial was conducted without any reagent, it was not possible to form a cake even after a long filtering time When a trial was performed after Hydrophobicize the clay with 0.7 kg / t (1.4 lb / ton) of hydrochloride of dodecylammonium at pH 9.3, the humidity was reduced to 32.3%. Time Cake formation was 13.4 minutes. When the hydrophobicity was improved using varying amounts of oil of sunflower, the humidity was also reduced, as shown in the Table 2. At 1.5 kg / t (3 lb / ton) of sunflower oil, the content of humidity was reduced to 22.4% and the cake formation time to 10.5 minutes The lipid was used as a 33% solution in diesel oil

TABLE 2 Effect of the use of sunflower oil in the Central Georgia kaolin clay dehydration

3

Example 3

A sample of Blackwater bituminous coal Mine, Australia, underwent a series of filtration tests Vacuum in laboratory. The sample was a flotation product and It was received in the form of an aqueous suspension. Because the bituminous coals are natural hydrophobes, the tests were performed without initial hydrophobicization. However, the humidity reduction was relatively poor, more likely due to the surface oxidation of the sample during transport. As a means of removing the oxidation product from the surface and recover, in this way, its hydrophobicity, the coal sample was wet milled for 1.5 minutes and was re-floated using a standard reagent package (i.e. 0.5 kg / t (1 lb / ton) of kerosene as collector and 0.1 kg / t (2 lb / ton) of methyl isobutylcarbinol (MIBC) as a foaming agent). The milling and flotation procedure can be considered as the first hydrophobicization stage disclosed herein invention.

Then the flotation product was conditioning for two minutes with several reagents that can further increase its hydrophobicity and, in this way, improve dehydration Three different reagents were used as hydrophobicity improvement reagents and the results. These include a vegetable lipid (soybean oil), Diesel oil and mixtures of the two. After the second stage of hydrophobicization, the carbon sample was subjected to a series of vacuum filtration tests using a 6.35 mm Buchner funnel (2.5 inches) in diameter, at 635 mm (25 inches) of Hg pressure vacuum, 1.14 cm (0.45 inches) cake thickness and 2 minutes of drying cycle time. Table 3 compares the results. A control test, in which the second stage of hydrophobicization, provided a cake moisture of 25.2%. Using 0.5 kg / t (1 lb / ton) of soybean oil in the second stage of hydrophobicization, the humidity was reduced to 20.2%. At more dosages high reagent, no additional improvements were obtained in the humidity reduction The use of diesel oil in the second hydrophobicization stage provided similar results. Using 1: 2 mixtures of the two oils provided higher degrees of humidity reductions In this case, the dosages of reagent provided in the first column of Table 3 is refer to the dosages of soybean oil (ingredient active) only, instead of the sum of the two oils. It can be suggested, therefore, that the behavior of 0.5 kg / t (1 lb / ton) of the mixture should be compared with the behavior of 1.5 kg / t (3 lb / ton) sunflower oil only or diesel oil only. Observe, however, that oil mixtures of soybean-diesel oil exceeded so much soybean oil as to sunflower oil individually even when compared based on total amounts of reagents used in the filtration experiments. For example, the use of a mixture of 0.5 kg / t (1 lb / ton) of soybean oil and 1 kg / t (2 lb / ton) of diesel oil provided 17.1% humidity, while 1.5 kg / t (3 lb / ton) soybean oil only and diesel oil only provided 20.5 and 20.1% cake moisture, respectively. This Thus, there is a synergistic effect using the mixture. Synergy increased with increasing dosages of reagent. As it shown in Table 3, the continued increase in Dosages of soybean oil only and sunflower oil only not considerably reduced the humidity of the cake, while a increase in the dosages of oil mixtures of soybean-diesel oil substantially improved the humidity reduction At 1.5 kg / t (3 lb / ton) of soybean oil As an active ingredient, cake moisture was reduced to a value as low as 14.3%. From a practical point of view, the oil diesel is substantially cheaper than soybean oil; for the therefore, the use of mineral oil can be considered as a low cost facilitator, which can greatly improve the lipid behavior, that is, soybean oil.

The reasons for the synergistic effect are not clear. It is possible that the triacylglycerols present in the oil of soybeans act as large surfactant molecules with a group of head (glycerol) and three hydrocarbon tails. Because they are insoluble in water, form large blood cells in water and act like a hydrocarbon oil, just like diesel oil. When soybean oil and diesel oil are used together, without However, the latter serves as a solvent for triacylglycerols and helps distribute them homogeneously in the surface of the carbon particles. Triacylglycerols they can be absorbed on the surface of the coal by hydrophobic interaction, and can improve your hydrophobicity. The contact angles can be increased up to about 90º or more of 90º, which leads to achieve high degrees of reduction of humidity. Another possible explanation may be that Triacylglycerols present in soybean oil facilitate the Diesel oil spread in coal. This can be achieved if the surfactant can reduce surface tensions in the diesel oil / water and oil / coal interfaces, while increasing the surface tension in the solid / water interface. The results net of the two possible mechanisms are the same, that is, the Hydrophobicity of coal increases with the combined use of a lipid of vegetable origin and a light hydrocarbon oil.

TABLE 3 Synergistic effect of the use of soybean oil and oil diesel for vacuum filtration of a carbon sample Blackwater (0.85 mm x 0)

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4

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Example 4

A sample of thick Pittsburgh coal from a Dense medium separator was pulverized by a shredder of jaw and a roller crusher, and then it was ground wet in a ball mill. The advantage of using a sample of fresh pulverized coal may be minimizing the harmful effect of surface oxidation. The ball mill product was screened at 0.5 mm, and the low flow of the sieve was subjected to flotation using 0.5 kg / t (1 lb / ton) of kerosene and 0.1 kg / t (0.2 lb / ton) of MIBC. The procedure of flotation is the first stage of hydrophobicization disclosed in the present invention The product was subjected to a second stage of hydrophobicization, in which a lipid (soybean oil) was used as hydrophobicity improving reagent. Because the lipids are insoluble in water, it may be beneficial to use them in conjunction with Various solvents In this example, several oils of Light hydrocarbons and a short chain alcohol. The essays of Filtration was performed using a 6.35 cm (2.5 vacuum filter) inches), to 1.14 cm (0.45 inches) cake thickness, 2 minutes of drying cycle time, and 635 mm (25 inches) thick cake. The results are provided in Table 4. With the sample of particular carbon used in this example, mineral oils They provided better results than butanol. Soybean oil dissolve the first one better. On the other hand, butanol is soluble in water, while mineral oils are not. Thus, It is not clear what makes soybean oil better solvent.

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TABLE 4 Effects of the use of soybean oil as an adjuvant of dehydration in various solvents in vacuum filtration of a sample of Pittsburgh coal (0.5 mm x 0)

5

Example 5

A flotation product of Peak Downs Mine, Australia was received as an aqueous suspension. The sample it oxidized superficially during transport. Therefore it was wet milled in a ball mill for 1.5 minutes and it was re-floated using 0.5 kg / t (1 lb / ton) of kerosene and 0.1 kg / t (0.2 lb / ton) of MIBC. The flotation product was conditioning with a lipid of animal origin (fish oil) to improve its hydrophobicity. The lipid was used as a solution to 33.3% in diesel oil. The conditioned carbon sample was subjected to a series of filtration tests at 200 kPa pressure of air and 2 minutes of drying cycle time. The results are provided in Table 5. At 0.64 cm (0.24 inches) thick cake and 2.5 kg / t (5 lb / ton) of fish oil, moisture is reduced from 23.4 to 9.4%, which represents a reduction in humidity of 59.8%. At lower reagent dosages and thicknesses of older cake, moisture reduction became less substantial.

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TABLE 5 Effects of the use of fish oil in filtration of a sample of coal (0.6 mm x 0) from Peak Downs Mine, Australia, at 200 kPa air pressure

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6

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Example 6

Table 6 shows the test results. vacuum filtration performed on a carbon sample Pittsburgh using fish oil as an adjuvant to dehydration It was used as a 1: 2 volume mixture with oil diesel. The carbon sample was a medium dense product, which was pulverized, ground in ball mill and sieved at 0.5 mm. The bass Screening flow was subjected to flotation using 0.5 kg / t (1 lb / ton) of kerosene and 0.1 kg / t (0.2 lb / ton) of MIBC before filtration. Filtration tests were performed using a Buchner funnel 6.35 cm (2.5 inches) in diameter, 635 mm (25 inches) of Hg vacuum pressure and 1.14 cm (0.45 inches) of cake thickness At 1.5 kg / t (3 lb / ton) of fish oil, the Humidity was reduced from 28.2 to 15.4%.

The angles of equilibrium contact of the treated Pittsburgh coal sample under different reagent conditions. In the absence of reagent, the carbon sample provided a contact angle of only 12 °, which which should generate relatively high capillary pressures and, for Therefore, a high cake moisture. At 0.5 kg / t (1 lb / ton) of Kerosene, the contact angle was increased to 44 °. According to Laplace equation, the increase in the contact angle from 12º to 44º should reduce capillary pressure by 1.36 times, which can be responsible for the modest reduction in moisture of the cake of  28.2 to 24.9%. These results can be considered as the consequence of the first hydrophobicization stage disclosed in the present invention In the presence of fish oil, the angle of contact increased to about 90 °, as shown in the Table 6. At 1 kg / t (2 lb / ton), it increased to 86º, which should reduce capillary pressure 14 times, compared to the case of coal not treaty. This large reduction in capillary pressure can be responsible for the substantial reduction in humidity from 28.2 to 16.2%. The results obtained after conditioning with oil fish can be considered as the consequence of the second hydrophobicization step disclosed in the present invention. The Table 6 also shows the surface tensions of the filtered. The reduction in surface tension with addition Increasing reagent may be another factor in the reduction observed in the moisture of the cake.

TABLE 6 Effects of kerosene and fish oil on contact angle of a Pittsburgh coal sample, tension surface of the filtrate and moisture of the cake final

7

Example 7

The various lipids of plant origin and animal should work with any solid moderately hydrophobe. Therefore, the filtration tests were made on a zinc concentrate (sphalerite) (0.105 mm x 0) obtained by flotation. The sample was received from a mine of zinc in Europe. However, it was found that the sample oxidized superficially during delivery. Therefore, the sample was re-floated using 0.05 kg / t (0.1 lb / ton) of isopropyl xanthate sodium and 0.075 kg / t (0.15 lb / ton) of MIBC as a means of regeneration of the fresh hydrophobic surface. The filtration tests were performed using a pressure filter 6.35 cm (2.5 inches) in diameter, at an air pressure of 100 kPa and 2 minutes of drying cycle time. Rehearsals were made at various dosages of a lipid (fish oil) and cake thickness. One part by volume of fish oil It was mixed with 2 parts of diesel oil before use. To 1.5 kg / t (3 lb / ton) of fish oil, moisture reductions were 46, 43 and 41% at 0.51 (0.2), 0.76 (0.3) and 1.52 cm (0.6 inches) of cake thickness, respectively. At 2.5 kg / t (5 lb / ton), moisture reductions did not improve much more.

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TABLE 7 Effects of the use of fish oil for filtration of a zinc concentrate at 100 kPa pressure air

8

Example 8

As another example, soybean oil was used as dehydration adjuvant for a copper concentrate (chalcopyrite) (150 mm x 0). The lipid was used as a solution to 33.3% in diesel oil. The sample was a flotation product, which oxidized superficially during transport. As a means to regenerate hydrophobic surfaces, the sample was milled in wet in a ball mill and was re-floated using 0.05 kg / t (0.1 lb / ton) of sodium isopropyl xanthate and 55 g / t (50 g / ton) of MIBC. The flotation product was subjected to tests of vacuum filtration using a 6.35 cm (2.5 cm Buchner funnel) inches), to 635 mm (25 inches) of Hg and 2 minutes of drying cycle The% of moisture reductions were 55, 43 and 43.4% at 0.38 (0.15), 0.76 (0.3) and 1.62 cm (0.6 inches) of cake thickness, respectively. Reagent additions greater than 1.5 kg / t (3 lb / ton) did not significantly increase the humidity reduction These results are comparable to obtained at the plant using a high pressure filter followed by a thermal dryer

TABLE 8 Effects of the use of soybean oil for filtration vacuum of a copper concentrate

9

Example 9

(Not an example of this invention)

Table 9 shows a set of trials of vacuum filtration performed on a sample of bituminous coal  (0.6 mm x 0) from Elkview Mine, British Columbia, Canada. The sample It was received in the form of an aqueous suspension and was used as He received. The tests were performed using a 6.35 Buchner funnel cm (2.5 inches) in diameter, 635 mm (25 inches) Hg of vacuum pressure, with 2 minutes of drying cycle time and 1.02 cm (0.4 inch) cake thickness. Three oils were used different vegetables as dehydration adjuvants and it They compared the results. These oils were used as solutions 10% in butanol. Both sesame oil and oil peanut reduced cake moisture by approximately 50% at 1 kg / t (2 lb / ton) reagent addition

TABLE 9 Effects of using different vegetable oils for Elkview coal vacuum filtration

10

Example 10

A flotation product (0.85 mm x 0) from Massey Coal Company, West Virginia, was used for filtration tests, in which a pressure filter with a diameter of 6.35 cm (2.5) was used inches), at 200 kPa of air pressure and 2 minutes of drying cycle The carbon sample was wet milled in a ball mill for 1.5 minutes and it was re-floated using 0.5 kg / t (1 lb / ton) of kerosene and 0.1 kg / t (0.2 lb / ton) of MIBC. Variable amounts of Coconut oil at different cake thicknesses. It was used as a 1: 2 mixture with diesel oil. The humidity reductions were 64.7, 58.5 and 51.2% at 0.51 (0.2), 1.02 (0.4) and 2.03 cm (0.8 inches)  of cake thickness, respectively.

TABLE 10 Effects of using coconut oil for filtration of a bituminous coal at 200 kPa pressure of air

eleven

Example 11

Dehydration adjuvants disclosed in The present invention work well with hydrophobic particles. He talc is a natural hydrophobic mineral that is used for a series of applications including paper coating and removal of Sticky wood pulp materials. Table 11 shows the results obtained in a series of filtration tests made using sunflower oil as an adjuvant of dehydration The reagent was used as a 33.3% solution in diesel oil The tests were performed using a filter of pressure of 6.35 cm (2.5 inches) in diameter, at 200 kPa pressure of air and 2 minutes of drying cycle time. The sample was received from Luzenac America, and was subjected to flotation using 0.1 kg / t (0.2 lb / ton) of MIBC just before filtration. Be achieved moisture reductions better than 50% to 0.51 (0.2) and 1.02 cm (0.4 inches) cake thickness. At 2.03 cm (0.8 inches) of cake thickness, the humidity was reduced from 28.4% to 16.3% using 2.5 kg / t (5 lb / ton) sunflower oil.

TABLE 11 Effects of the use of sunflower oil for filtration of a talc sample (0.15 mm x 0) at 200 kPa of  air pressure

12

Example 12

In this example, a clear spiral product was wet ground in a ball mill. The finest fractions (0.85 mm x 0) were subjected to flotation using 0.5 kg / t (1 lb / ton) of kerosene and 0.1 kg / t (0.2 lb / ton) of MIBC as a means of initial hydrophobicization. The hydrophobicity of the flotation product was improved using an animal lipid (lard) and then underwent filtration tests. Be performed two sets of tests at 100 and 200 kPa pressure of air. Variable amounts of lipid were used as solutions to 25% in diesel oil. The tests were performed using a filter of 6.35 cm (2.5 inches) in diameter at 2 minutes of cycle time drying As shown in Table 12, butter oil Pork works well as a dehydration aid. The reduction of humidity improves with air pressure and reagent dose growing Moisture reductions of 50 to 60% at lower were obtained cake thickness and higher air pressure. Even with the cake more thick, moisture reductions were obtained that approximated the 50% at higher reagent dosages.

TABLE 12 Effects of the use of lard oil for filtration of a 0.85 mm x 0 Massy carbon sample at 100 and 200 kPa air pressure

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Example 13

In this example, a part by volume of oil of sunflower was mixed with a part of sorbitan monooleate (Span 80) and four parts of diesel oil and was used as an adjuvant dehydration The HLB number of sorbitan monooleate is 4.3; therefore, it mixes well with the other two components. The dehydration tests were performed on a carbon sample bituminous from Massey Coal Company, West Virginia. It was a product dense medium, which was fractured, ground and sieved to obtain a 0.6 mm fraction x 0, which was subjected to flotation using 0.5 kg / t (1 lb / ton) of kerosene and 110 g / t (100 g / ton) of MIBC. The dehydration tests were performed using a pressure filter 6.35 cm (2.5 inches) in diameter, at 150 kPa air pressure,  at 2 minutes of pressure cycle time and 1.27 cm (0.5 inches) of cake thickness. The tests were performed by Variable reagent dosages.

The results obtained with the oil mixture of sunflower-sorbitan monooleate were compared with those obtained with their individual components. Oil sunflower provided considerably lower results than obtained with sorbitan monooleate. However, the results obtained with a mixture of the two were comparable to obtained with sorbitan monooleate. This discovery suggests that the mixture of an appropriate lipid and a low HLB surfactant provides a means to reduce the cost of reagent, since the First is cheaper than the last.

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TABLE 13 Effects of using a mixture of oil sunflower-sorbitan monooleate for filtration of a sample of bituminous coal at 150 kPa pressure of air

14

Example 14

Although the results obtained using the dehydration adjuvants disclosed in the present invention produced results far superior to those obtainable using conventional dehydration adjuvants, their effectiveness decreases With the thickness of cake growing. This is probably a reflection. of the difficulty in transporting water molecules released by dehydration adjuvants disclosed in the present invention through the filter cake. A solution of the problem may be to apply a mechanical vibration to the cake of filtered during the drying cycle time. Table 14 shows the results obtained, with and without the use of vibration, when used sunflower oil as a dehydration aid for filtration of a carbon sample (0.6 mm x 0) from Virginia. He Reagent was used as a 33.3% solution in diesel oil. The coal sample was a medium dense product, which was fractured, ground and flotted using 0.5 kg / t (1 lb / ton) of kerosene and 0.1 kg / t (0.2 lb / ton) of MIBC. The experiments of filtration were performed using a 6.35 cm Buchner funnel (2.5 inches) in diameter, at 635 mm (25 inches) of Hg pressure of emptiness. An ultrasonic probe was placed in the conical part of the Buchner funnel during the drying cycle time of 5 minutes. When the vibration was applied without the dehydration adjuvant, the Cake moisture was reduced from 22.6 to 19.2%. When 1 was used kg / t (2 lb / ton) of the dehydration adjuvant in conjunction with the vibration, the humidity of the cake was reduced to 9.2%, to 1.02 cm (0.4 inches) cake thickness. At 2.5 kg / t (5 lb / ton), the Humidity was reduced to 7.7%.

TABLE 14 Effects of vibration on the filtration of a Virginia coal using sunflower oil as an adjuvant to dehydration

fifteen

Example 15

Several surfactants are used to reduce the surface tension of water that must be removed by filtration. According to the Laplace equation, this should reduce the water pressure trapped in the capillaries present in a cake of filtering and, in this way, should help reduce humidity of the residual cake. It should be noted, however, that the greatest part of the water is easily removed during the formation time of the cake or through the largest capillaries present in the cake. In this sense, the amount of reagent dissolved in the part of the water that is easily removed can be considered as a waste. It would be cheaper to add the reagent after A cake has formed. This will serve as a means to add the reagent when really needed.

In this example, a series of trials spraying butanol directly on a cake filtered out. Approximately 1 kg / t (2 lb / ton) of reagent was added immediately after the cake formation time. The surface tension of butanol is 20.6 mN / m at 20 ° C, which is very lower than that of water. Therefore, the role of butanol can be to reduce the surface tension of the water trapped in the thinner capillaries. The carbon sample used in this example was a middle dense middle fork product, which was crushed, ground and flotted using 0.5 kg / t (1 lb) of kerosene and 0.075 kg / t (0.15 lb / ton) of MIBC. The flotation product was conditioning with varying amounts of a lipid (oil from sunflower) prior to filtration. The filtration tests are performed using a 6.35 cm (2.5 inch) Buchner funnel of diameter, at 635 mm (25 inches) of Hg vacuum pressure, 2 minutes of drying cycle time and 1.65 cm (0.45 inches) of cake thickness As shown in Table 15, the technique of spraying reduced cake moisture between 4 and 5% more of which can be achieved using the lipid as a reagent hydrophobicity improver. In this way, the technique of using lipids and butanol spray provides a means of get deep moisture reductions. Any other reagent surface tension reducer can be sprayed instead of butanol used in this example. Care should be taken, however, of not using surfactants that can buffer hydrophobicity of the particles to be dehydrated.

TABLE 15 Effects of combining the techniques of using oil sunflower and butanol spray to get deep moisture reductions to 1.65 cm (0.45 inches) thick cake

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Example 16

It is the objective of the present example to demonstrate that combining the procedures of using a lipid to improve the hydrophobicity and spraying butanol to reduce stress Superficial moisture reductions can be achieved at A big cake thickness. The vacuum filtration tests were made on a sample of bituminous coal from Massey Coal Company, West Virginia, at a cake thickness of 3.56 (1.4 inches). The carbon sample was a medium dense product, which was crushed, ground and sieved to obtain a fraction of 0.6 mm x 0. The low flow of the sieve was subjected to flotation using 0.5 kg / t (1 lb / ton) of kerosene and 0.075 kg / t (0.15 lb / ton) of MIBC. The Filtration tests were performed using a Buchner funnel of 6.35 cm (2.5 inches) in diameter, with a height of 16.5 cm (6.5 inches), at a vacuum pressure of 635 mm (25 inches) of Hg and a drying cycle time of 2 minutes. The control test, which  was performed on the flotation product without lipid or butanol spray, provided a cake moisture of 25.8%, as shown in Table 16. At 1.5 kg / t (3 lb / ton) of sunflower oil and 1 kg / t (2 lb / ton) of butanol spray, cake moisture was reduced from 25.8 to 13%.

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TABLE 16 Effects of combining the techniques of using oil sunflower and butanol spray to get deep moisture reductions to a cake thickness of 3.56 cm (1.4 inches)

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Example 17

A rather surprising observation was made when aluminum ions (Al 3+) were used in conjunction with dehydration adjuvants disclosed herein invention. It has been found that in the presence of the coagulant well known for negatively charged particles, quantities of lipids required to achieve cake moisture desired were greatly reduced. The second column and the third column of Table 17 compare the results obtained using or without using Al 3+ ions before filtration. In each experiment, an aqueous suspension of carbon was conditioned in presence of 0.01 kg / t (0.02 lb / ton) of aluminum chloride during 2 minutes before adding the desired amount of sunflower oil. The coal sample was a dense medium product of the plant coal preparation Middle Fork, Virginia. It was crushed, ground and screened to obtain a fraction of 0.6 mm x 0, which was subjected to flotation using 0.5 kg / t (1 lb / ton) of kerosene and 0.1 kg / t (0.2 lb / ton) of MIBC. The flotation product was filtered using a Buchner filter 6.35 cm (2.5 inches) in diameter, at 1.70 cm (0.67 inch) cake thickness and a drying cycle time 5 minutes As shown, the cake moisture achieved using both Al 3+ ions and a lipid (sunflower oil) are far inferior to those of the case in which the latter is used only. Consequently, the amount of sunflower oil required for getting a certain level of cake moisture was reduced substantially in the presence of Al 3+ ions. For example, it they needed 2.5 kg / t (5 lb / ton) of sunflower oil to get a cake moisture of 12.3% in the absence of Al 3+ ions. In the presence of Al 3+ ions, however, only they needed 0.25 kg / t (0.5 lb / ton) of sunflower oil to achieve a cake moisture of 12.6%. When 1 was sprayed kg / t (2 lb / ton) of butanol, dehydration became even more Effective: the amount of sunflower oil required to get a cake moisture of 12.3% was further reduced to 0.125 kgt (0.25 lb / ton), as shown in the third column of the Table 16.

Dehydration became even more efficient when the filter cake was subjected to vibration during the 5 minute drying cycle time. As shown in the last column of Table 17, the humidity of the cake was reduced to 10.3% at 0.125 kg / t (0.25 lb / ton) of sunflower oil. Older sunflower oil dosages, dampness of single digit cake. In this way, the combinations appropriate to: i) use the dehydration adjuvants disclosed in the present invention, ii) conditioning the aqueous suspension with trivalent (or divalent) cations, iii) spray an agent or appropriate surface tension reducing agents during the drying cycle time, and iv) apply mechanical vibration During the drying cycle time, it can help to get deep levels of moisture reduction using small amounts of lipids as dehydration adjuvants.

TABLE 17 Effects of combining the techniques of using oil sunflower, Al 3+ ions, spray butanol and vibration to get deep moisture reductions to a cake thickness of 1.70 cm (0.67 inches)

18

Claims (20)

1. Dehydration procedure of a aqueous suspension of fine particulate material that is smaller than 2 mm in diameter, whose procedure includes the stages from:

i)

convert fine particulate material into moderately hydrophobic increasing its contact angle to 25º to 60º interval in a hydrophobicization stage initial,

ii)

add a lipid dissolved in an appropriate solvent or solvent mixtures,

iii)

stir the aqueous solution to allow the lipid molecules are absorbed on the surface of the material moderately hydrophobic, so that its hydrophobicity is improved and the contact angle is increased above 60 °, and at continuation

iv)

submit the conditioned aqueous suspension that Contains the particulate material, whose water contact angle has been increased, to a mechanical dehydration procedure suitable.

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2. Method according to claim 1, in which the initial hydrophobicization in (i) is achieved using appropriate collectors and surfactants. 3. Method according to claim 1, in which the initial hydrophobicization stage (i) involves creating cool surfaces by spraying and / or wear, when the fine particulate material to dehydrate is coal or other material natural hydrophobic 4. Method according to claim 1, in that the fine particulate material to dehydrate is a material whose surface has become less hydrophobic due to aging or to surface oxidation. 5. Method according to claim 1, in which the fine particulate material includes minerals, coal, inorganic pigments, plastics, metals, metal powders, ash Flyer and biological materials. 6. Procedure according to any one of the previous claims, wherein said mechanical process suitable dehydration includes vacuum filtration, filtration at pressure, centrifugal filtration and centrifugation. 7. Procedure according to any one of the previous claims, wherein the lipid is selected from among various vegetable oils, plant oils, oils from fish and animals, fats, steroids and waxes. 8. Procedure according to any one of the previous claims, wherein the lipid is mixed with a non-ionic surfactant balance number hydrophilic-lipophilic less than 15. 9. Procedure according to any one of the previous claims, wherein said appropriate solvents include light hydrocarbon oils, short chain alcohols and ethers. 10. Method according to claim 2, in wherein said appropriate surfactants are high HLB surfactants, whose polar heads can interact with the surface of the particulate materials 11. Method according to claim 2, in which said collectors are thiols for metals and minerals sulfurized 12. Method according to claim 2, in which said collectors are hydrocarbon oils when the particulate material is carbon or other hydrophobic substance natural. 13. Procedure according to any one of the previous claims, wherein an electrolyte or a mixture of electrolytes selected from anion salts and monovalent, divalent and trivalent cations after the stage of initial hydrophobicization (i) and before stage (ii), so that the amount of lipids required to achieve moisture Desired particulate material is substantially reduced. 14. Method according to claim 13, in which said electrolytes are the salts of the ions of aluminum. 15. Method according to claim 13 or 14, in which the reagents used in step (i) and step (ii) and said electrolyte or mixture of electrolytes can be added in a single stage 16. Procedure according to any one of the claims 1 to 12, wherein the mechanical method of proper dehydration is a filtration procedure in which the filter cake is subjected to an appropriate vibrating means, of so that a greater degree of moisture reduction is achieved at a cake thickness determined.

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17. Method according to claim 16, in which appropriate vibrating means include means ultrasonic, mechanical and acoustic. 18. Procedure according to any one of the claims 1 to 12, wherein the mechanical method of proper dehydration is a filtration procedure in which a suitable surface tension reducing reagent is added to the filter cake, in the form of fine mist or spray, of so that a higher level of moisture reduction is achieved at a cake thickness determined. 19. Method according to claim 18, in that the appropriate surface tension reducing agent is selected from among short chain alcohols, oils appropriate light hydrocarbons and surfactants. 20. Procedure according to any one of the claims 13 to 15, wherein the mechanical method of proper dehydration is a filtration procedure in which a suitable surface tension reducing reagent is added to the filter cake, in the form of fine mist or spray, and when at the same time, the filter cake is subjected to a vibrating medium appropriate, so that a substantial reduction of moisture to a large cake thickness using minimal amounts of reagents