JPH0439511B2 - - Google Patents

Description

Claim 1: An aqueous slurry of a solid fuel in the form of a finely divided carbonaceous material having a maximum particle size of about 0.5 mm and at least one additive in an amount of 0.02 to 2% by weight, wherein the solid content of the slurry is 65 to 2% by weight. In an aqueous slurry that is 90% by weight,
The additive has the following formula: RO( _CH2CH2O ) _oH , where R is () an aliphatic group having 10 to 24 carbon atoms, () _an acyl group having 10 to 24 carbon atoms base,
or () a substituted aryl group having 12 to 54 carbon atoms, where n is () 40 to less than 100, or () 40 to 200 and a pair of ethyleneoxy units R
The ratio of the number of carbon atoms in the group is 3.5 to 6.0 when R is an aliphatic group or an acyl group, and 3.0 to 5.5 when R is a substituted aryl group). A 20°C aqueous solution containing an alkylene oxide adduct has a surface tension of 5×10 ^-3 N/m or less measured according to the Giunouill ring method, is chemically reacted to modify the surface properties, and is carbonaceous. An aqueous slurry characterized in that carbonaceous materials containing at least 0.1% by weight or more of hydrophobic materials based on the material are excluded. 2. The aqueous slurry according to claim 1, wherein n is 50 or more and less than 100. 3 n is 50 to 150 and ethyleneoxy unit pair R
The ratio of the number of carbon atoms in the group is 3.5 to 6.0 when R is an aliphatic group or an acyl group, and when R is a substituted aryl group.
The aqueous slurry according to claim 1, which has a molecular weight of 3.0 to 5.5. 4 The alkylene oxide adduct has the following formula, The aqueous slurry according to claim 1, wherein R ₁ is an alkyl group, R ₂ is an alkyl group or a hydrogen atom, and n is the same number as above. 5. The aqueous slurry according to claim 4, wherein the alkylene oxide adduct is a dialkyl-substituted phenyl compound. 6 The alkylene oxide adduct is added to the above slurry.
Aqueous slurry according to claim 1, present in an amount of 0.05 to 0.8% by weight. 7. An aqueous slurry of solid fuel in the form of a finely divided carbonaceous material with a maximum particle size of about 0.5 mm and 0.02 to 2% by weight of at least one additive, wherein the solid content of the slurry is 65 to 90% by weight. In an aqueous slurry manufacturing process, the following steps are included: a) wet milling the carbonaceous starting material with water to a solids content of 20 to 50% by weight in at least one milling step; c. dewatering the carbonaceous material to a solids content substantially equal to the solids content of the final slurry, and d applying the following formula to the dehydrated carbonaceous material: RO(CH ₂ CH ₂ O) _o H (R in the formula is () an aliphatic group having 10 to 24 carbon atoms, () an acyl group having 10 to 24 carbon atoms, or () having 12 to 54 carbon atoms Substituted aryl group, n is () 40 or more and less than 100, or () 40 to 200, and the ratio of the number of carbon atoms in the ethyleneoxy unit to the R group is 3.5 to 6.0 when R is an aliphatic group or an acyl group. , R is 3.0 to 5.5 when R is a substituted aryl group) is added and dispersed, and the alkylene oxide adduct dissolves the alkylene oxide adduct. °C as an aqueous solution with a surface tension of not more than 5 x 10 ^-3 N/m, measured according to the method according to Giunouill's ring, and which has been chemically reacted to modify the surface properties and contains at least 0.1% by weight relative to the carbonaceous material. A method for producing an aqueous slurry, characterized in that carbonaceous materials containing the above hydrophobic materials are excluded. 8. The manufacturing method according to claim 7, wherein n is 50 or more and less than 100. 9 n is 50 to 150 and ethyleneoxy unit pair R
The ratio of carbon numbers in the group is 3.5 to 6.0 when R is an aliphatic group or an acyl group, and 3.0 to 6.0 when R is a substituted aryl group.
5.5, the manufacturing method according to claim 7. 10 The alkylene oxide adduct has the following formula, (R ₁ in the formula is an alkyl group, R ₂ is an alkyl group or a hydrogen atom, and n is the same number as above)
The manufacturing method according to claim 7, which is represented by: 11. The production method according to claim 7, wherein the alkylene oxide adduct is a dialkyl-substituted phenyl compound. 12 The alkylene oxide adduct is added to the above slurry.
A method according to claim 7, wherein the method is present in an amount of 0.05 to 0.8% by weight. Description The present invention relates to an aqueous slurry of solid fuel in the form of micronized carbonaceous material and at least one surfactant. The present invention also relates to a method for producing such an aqueous slurry. "Solid fuel" as used in the present invention includes various types of carbonaceous materials such as bituminous, anthracite, subbituminous and lignite, charcoal, petroleum coke or other solid by-products of refineries. Today, the generation of heat is mostly based on the combustion of liquid or gaseous fuels, thus making the existing Plato in its physical form suitable for transporting, storing and burning fuels. Conversion to lump coal involves extensive renovation and new investment, so it is not surprising that there has been significant interest in various methods for converting coal into liquid or gaseous fuel products. In addition to chemically converting coal to methanol or hydrocarbons, it has also been proposed to produce slurries of coal powder and various liquids, such as methanol, oil, a mixture of water and oil, or just water. Of these, coal-water-oil slurries have significant practical and economic advantages over the others, primarily because they have a high flash point and low raw material costs for the liquid carrier medium. It's for a reason. Many demands are placed on the coal/water slurry, but the most important requirements are that the slurry have a high carbon content and be homogeneous even after it has been stored for some time. Additionally, it is important to reduce the viscosity of the slurry to facilitate pumping and comminution of the slurry within the combustion chamber. The slurry must also have low sensitivity to changes in PH and low corrosiveness to tanks, pipelines, pumps and nozzles. It is already known to produce slurries of finely divided solid fuels and to increase or decrease the stability of these slurries by means of various additives. An example of the prior art is U.S. Pat. No. 4,217,109, which uses selective adsorption to separately charge coal particles and particles of other materials, thereby refining the coal and stabilizing the suspension. A coal/water slurry is disclosed that contains a dispersant that facilitates dispersion. The dispersant in this US patent is selected from polyelectrolytes or polyphosphates. Furthermore, the published PCT application PCT/US80/
01419, it is already known that a highly concentrated slurry of coal and water can be produced by controlling the particle size distribution of the coal in a special way and adding a surfactant that imparts a specific surface charge to the coal particles. It is being The surfactants used are commercially available dispersants. The characteristics of the slurry are highly dependent on the combination of precise particle size distribution and interfacial charge of the individual particles, which is achieved by adding precise amounts of dispersant. However, in practical implementation, it is difficult to achieve the required exact particle size distribution reproducibly and on an industrial scale, or to increase the ionic contamination of the slurry due to equipment corrosion or coal leaching, for example. It is extremely difficult to maintain the characteristics. Furthermore, from the Specification of Slance Patent No. 1308112,
It is already known that the viscosity of low-thick coal suspensions can be reduced by using alkylene oxide adducts in which the hydrophilic part preferably consists of 5 to 35 ethylene oxide units. GB 1429934 relates to a method for dispersing particulate material in a liquid by means of a block copolymer constituted by blocks which are respectively soluble and insoluble in the liquid. Poly(t-butylstyrene) is cited as an example of a soluble block. Particulate material is very fine particles, preferably having a particle size of 50ⓓ to 10 μm. One example of a particulate material is carbon black. U.S. Patent No. Published November 9, 1982
No. 4358293 and the corresponding EPC application no. 82300448.6, publication no. 0057576, published on August 11, 1982, disclose that nonionic surfactants having at least 100 repeating ethylene oxide units are used as dispersants. An aqueous coal dispersion system is disclosed. According to these references, surfactants having less than 100 repeating ethylene oxide units are said to be ineffective or insufficiently effective. This teaching is contrary to the results of applicant's own research as reported herein. The present invention aims to improve the viscosity and stability of highly concentrated aqueous slurries of pulverized carbonaceous solid fuels. Here, highly concentrated slurry is 65 to 90% by weight,
Preferably it means an aqueous slurry containing 70-80% by weight solids. To achieve this purpose, the formula RO(CH ₂ CH ₂ O) _o H (where R is an aliphatic or acyl group having 10 to 24 carbon atoms or an acyl group having 12 to 54 carbon atoms) is used. Substituted aryl group having: n is 40 to less than 100, or n is 40 to 200; in the latter case, the ratio of the ethyleneoxy unit to the number of carbon atoms in the R group is 3.5 when R is an aliphatic group or an acyl group; ~6.0, 3.5 to 5.5 when R is a substituted aryl group) are incorporated into the aqueous slurry. Here, "surfactant" means that an aqueous solution of 0.1% alkylene oxide adduct at 20℃ is 50dyn/
It has a surface tension of less than cm. Incidentally, this surface tension is measured according to Giunouill's ring method. Particularly suitable are alkylene oxide adducts with a surface tension of 40 to 49 dyn/cm. The surface-active ethylene oxide adduct having the above-mentioned composition composed of a hydrophobic part and a hydrophilic part is such that the hydrophobic part of the ethylene oxide adduct adsorbs on the surface of the fuel particles, while the hydrophilic part of the ethylene oxide adduct adsorbs on the surface of the fuel particles. Steric stabilization of the highly concentrated fuel slurry of the present invention can be achieved by the polyethylene oxide chains binding the aqueous phase to the surface of the fuel particles. If the surface of each particle is covered with adsorbed alkylene oxide adducts,
Each fuel particle in the aqueous slurry is surrounded by such a bound water layer. This layer of water surrounding each fuel particle reduces the internal friction of the aqueous slurry so that the particles can achieve a sliding motion past each other, the motion being unaffected by attractive forces between the particles. Furthermore, steric stabilization according to the present invention is less sensitive to changes in the concentration levels of various salts in the aqueous slurry. The features of the invention will be apparent from the claims. Accordingly, one aspect of the invention includes a solid fuel in the form of a finely divided carbonaceous material and from 0.02 to 2% by weight of at least 1
The purpose of the present invention is to prepare an aqueous slurry with a seed additive, the solid content of the slurry being between 65 and 90% by weight, and the aqueous slurry having an additive of the following formula: RO(CH ₂ CH ₂ O) _o H (in the formula R is an aliphatic group or acyl group having 10 to 24 carbon atoms, or a substituted aryl group having 12 to 54 carbon atoms; n is 40 to less than 100, or n is 40 to 200, in the latter case The ratio of ethyleneoxy units to the number of carbon atoms in the R group is 3.5 to 6.0 when R is an aliphatic group or an acyl group, and 3.0 to 5.5 when R is a substituted aryl group). It is characterized by containing an alkylene oxide adduct. Another aspect of the present invention is to provide a method for producing an aqueous slurry of solid fuel in the form of pulverized carbonaceous material and 0.02 to 2% by weight of at least one additive, the solids content of the slurry being is between 65 and 90% by weight and the following steps are taken: a. Wet milling the carbonaceous starting material with water to a solids content of 20 to 50% by weight in at least one milling step; b. c. dewatering the carbonaceous material to a solids content substantially equal to the solids content of the final slurry; d. adding the following formula to the dehydrated carbonaceous material: RO(CH ₂ CH ₂ O); _o H (R in the formula is an aliphatic group or acyl group having 10 to 24 carbon atoms, or a substituted aryl group having 12 to 54 carbon atoms; n is 40 to 100
or n is from 40 to 200; in the latter case, the ratio of ethyleneoxy units to the number of carbon atoms in the R group is from 3.5 to 3.5 when R is an aliphatic group or an acyl group.
6.0 or 3.0 to 5.5 when R is a substituted aryl group) is added and dispersed. As mentioned above, the present invention provides a concentrated aqueous slurry, i.e. at least 65-90% by weight, preferably 70-80% by weight.
It must be emphasized that the slurry has a solids content of . This means that water is only present in the slurry in an amount of less than 35% by weight, preferably 20-30% by weight. Applicants have discovered that many of the properties and claimed advantages obtained by the prior art relate to relatively low-thickness slurries having at least about 40% water by weight, and that it is possible to simultaneously increase the solids content to over 65% by weight. It has been found that it is impossible to maintain slurry pumpability and stability. However, it has surprisingly been found that these problems can be overcome by adding a specific water-soluble surfactant compound consisting of an ethylene oxide adduct having a hydrophobic part and a hydrophilic part. In addition, the above-mentioned water-soluble surfactant compound has a hydrophilic portion of 40 or more and less than 100, suitably 50 or more and less than 100,
preferably 50 to 90 ethyleneoxy units, or
consisting of polyethylene oxide chains having a chain length of either 40 to 200, preferably 50 to 150 ethyleneoxy units, in the latter case the ratio of ethyleneoxy units to the number of carbon atoms in the R group in said formula is When R is an aliphatic group or an acyl group, it is 3.5 to 6.0, and when R is a substituted aryl group, it is 3.0 to 5.5, that is, the hydrophilic part consists of a hydrophilic chain having a predetermined length. . The most preferred range is 60 to 90 ethyleneoxy units. This length of hydrophilic chain has been found to be an essential condition in order to achieve a stable and low viscosity, ie, to make the fuel slurry pumpable at solids content above 65% by weight. The stability of the slurry, i.e., the resistance to separation of solids and water during storage and transportation of the slurry with vibration of the slurry, increases as the number of ethylene oxide units in the hydrophilic portion increases, i.e., as the number of ethylene oxide units in the hydrophilic part increases. Such stability increases as the length increases. However, if the hydrophilic chains are too short (number of ethylene oxide units less than 40), separation and sedimentation will occur if the slurry is subjected to vibration for several days. In addition to the hydrophilic parts as mentioned above, the surface-active compounds according to the invention also have hydrophobic parts, which parts are adapted for adsorption onto the surface of the finely divided carbonaceous material. The compounds according to the invention can be prepared by reacting a suitable amount of ethylene oxide in a well-known manner with a suitable organic compound having hydrogen, carbon and oxygen as constituents and having hydrogen which is reactive with ethylene oxide. Obtainable. Examples of suitable organic compounds of this type include decyl alcohol, lauryl alcohol, myristyl alcohol, cetyl alcohol, stearyl alcohol, eicosyl alcohol, oleyl alcohol, cyclododecanol, cyclohexanedecanol, octylphenol, nonylphenol, dodecylphenol, Hexadecylphenol, dibutylphenol, dioctylphenol,
These are dinonylphenol, didodecylphenol, dihexadecylphenol, trinonylphenol, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid and arachidic acid. Examples of other specific surfactants according to the present invention are as follows: (In the formula, R ₁ is an alkyl group, R ₂ is an alkyl group or a hydrogen atom, n is 40 or more and less than 100, suitably 50
100 or more, preferably 50 to 90, or n is 40
-200, preferably 50-150, and in the latter case the ratio of carbon atoms of ethyleneoxy units to substituted phenyl groups is 3.0-5.5). Disubstituted compounds are particularly preferred, and even more particularly disubstituted compounds in which R ₁ and R ₂ are nonyl groups. The concentration of additives in the aqueous slurry, such as surface-active compounds according to the invention, is
The amount is 0.02-2% by weight. The concentration of surface-active compounds according to the invention is between 0.05 and 0.8% by weight of the slurry. Besides the particular surfactant compounds according to the invention mentioned above, other customary additives which enhance the effect of the surfactant compounds according to the invention or bring about other effects, such as antibacterial agents, anti-foaming agents, PH-regulating agents. , and conventional stabilizing agents may also be incorporated into the slurry. The addition of conventional stabilizers is particularly suitable when the hydrophilic portion of the dispersant is relatively short. Examples of common stabilizers include protective colloids such as xanthan gum, cellulose derivatives such as carboxymethylcellulose, ethylhydroxyethylcellulose, hydroxyethylcellulose, clays such as attapulgiyaite, sepiolite, bentonite,
Aluminum hydroxide, silica gel, cellulose suspension, carbon black, starch and starch derivatives. If other additives are used in addition to the special surface-active compounds, customary stabilizers should be added to a concentration of at most 1% by weight, preferably at most 0.2% by weight, while antifoaming agents at most 0.1
It is customary that it should be added up to a concentration of % by weight. However, all values are based on the weight of the slurry. The PH regulator is preferably an alkali metal hydroxide, such as sodium hydroxide, and the PH regulator is added in an amount such that the PH of the slurry is on the alkaline side, e.g. PH 10 or higher, thereby improving transport and storage equipment. Solve corrosion problems. Furthermore, the aqueous slurry of the present invention contains as a main component a solid fuel in the form of a finely divided carbonaceous material. As already mentioned, carbonaceous materials include bituminous coal, anthracite coal, subbituminous coal,
Choose between lignite, charcoal and petroleum coke. If the solids content conditioned by additives is ignored, the content of finely divided carbonaceous material in the slurry is equal to the solids content of the slurry, i.e. it is 65-90% by weight relative to the total weight of the slurry. , preferably 70 to 80% by weight. Micronized carbonaceous materials do not require any treatment to alter their hydrophobicity. Rather, it is preferable to maintain the surface of the carbonaceous material in an unmodified state, i.e. the surface does not undergo any chemical reactions that alter its surface properties, and it is preferable to add hydrocarbons, such as fuel oil, that impart hydrophobicity to the carbonaceous material. preferably against
It contains less than 0.5% by weight, more preferably less than 0.1% by weight. The particle size of the micronized carbonaceous material plays an important role in considering the stability of the slurry of the present invention. Several problems are required to be solved at optimal granularity. First of all, solid fuels with impurities, such as coal, must be beneficent to remove inorganic impurities from the organic material. The particle size must be adapted so that the release of impurities is satisfactory. Second, the fuel slurry is preferably 100-250μ to ensure complete combustion of fuel particles in the flame.
It should have a particle size of less than m. Also 100μm
It is preferable to limit the particulate content in excess of 30% to minimize wear on burners and similar equipment handling the slurry. Third, of course, the particle size distribution must be maximized with maximum stability, minimum viscosity, and minimum water content of the slurry. The above requirements regarding particle size distribution are not as critical as would normally be the case in highly concentrated aqueous slurries of solid fuels due to the favorable properties of the particular surface-active compounds of the present invention, and the present invention is less critical under industrial manufacturing conditions. Constant variations in particle size distribution, as is usual, can be accommodated without compromising the viscosity or stability of the slurry. More particularly, it has been found that for the present invention the particle size should be in the range from 0.1 to 350 μm, preferably from 1 to 250 μm. However, for best results, the particle size should be about 200 μm or less. For some applications, such as combustion of the fuel slurry in a fluidized bed or injection of the fuel slurry into a blast furnace, the particle size of the pulverized carbonaceous material is not particularly critical, and even if the fuel slurry contains relatively large particles it is problematic. It never happens. However, the particle size should not exceed about 0.5 mm because there is a risk that the particles will settle if they are too large. The present invention has been described in terms of solid fuel aqueous slurries. The method for making the aqueous slurry of the present invention is described with respect to solid fuel in the form of bituminous coal. The basic technology is the same as for other solid fuels, such as subbituminous coal, anthracite and lignite, charcoal, petroleum coke, etc.
This is true even though these types of fuels are not necessarily treated in the same manner. Therefore, although some solid fuels do not require the refining steps described below that apply to coal, in some cases the mechanical properties of the various types of coal may make them different from the equipment described below for bituminous coal. A pulverizer is required. A suitable starting material is bituminous coal which has been pulverized to a certain degree and subjected to primary beneficiation in a conventional manner so as to reduce the non-water inorganic content of the coal to about 5-20% by weight. The product obtained is then milled in a conventional manner to a particle size suitable for a first milling step. It is preferable that this pulverization step is a wet pulverization operation using a ball or rod mill. This first milling step achieves three objectives: 1. Milling to maximum particle size for sufficient release of inorganic impurities in the coal. 2. Finely ground to the maximum particle size suitable for the intended use, already to a particle size that can be completely combusted in a reaction zone, for example in a flame. 3. Finely ground to a particle size distribution appropriate to the rheological properties of the fuel. The conditions that must be met to achieve objectives 1 and 2 are, on the one hand, due to the mineralogy of the coal;
On the other hand, it is determined by the method of application. As mentioned above, a particle size of approximately 0.5 mm should not be exceeded and usually
A particle size of 350 μm should not be exceeded. Generally, a maximum particle size of about 100-200 μm is preferred. With respect to particle size distribution, it is well known that the particle size distribution of a collection of particles can be optimized to minimize the porosity of the collection of particles, ie the volume not occupied by solid material. In the present invention, there are no absolute requirements regarding the specific distribution in order to obtain a composition with low moisture content, low viscosity and sufficient stability. Studies of many types of coal have shown that, depending on the type of coal and the milling method, different compositions of particle shapes can be identified in the particle aggregate after the milling operation. This applies for all coal types and for all pulverization operations,
This means that there is a predetermined particle size distribution that provides optimum moisture content and optimum viscosity for the milling circuit and the type of milling contained therein, and such particle size distribution can be established by one skilled in the art. Additionally, the particle geometry of the composition can affect rheology and stability. It is therefore possible to choose a certain type of milling for the milling circuit, giving the most advantageous locations, for example, to equiaxed grains or discoidal and flake-shaped grains, thereby influencing the final properties of the composition. It can be influenced to suit each particular application. However, it is an important aspect of the present invention that the stabilizing and viscosity reducing agents for producing useful low moisture fuels are not critically determined by a particular particle size distribution. On the other hand, while it is advantageous to achieve a particle size distribution that maximizes the solids content within the composition according to known principles, further advantages are obtained by controlling the shape of the particles. The tendency for different geometries to be imparted to the particles by different mill types is illustrated below: - Hammer mill: favors equiaxed particles in the pulverization of bituminous coal. - Wet pulverization using a rod mill: Advantageous for producing irregularly pointed acicular particles during pulverization of bituminous coal. - Szego mill (manufactured by General Communities, Toronto, Canada): flat, flaky particles from the fine grinding of bituminous coal. Some examples of suitable particle size distributions are listed below: 1 Bituminous coal from United Coal Companies, Virginia, USA (Widow Kennedy Seam) Composition : Fixed carbon: 65% Volatile components: 28% Mineral components: 7% The following particle size distribution gives a final composition with a solids content (total fraction of solid matter, weight % of dry article) of up to 83.5%: Less than 200 μm 100% Less than 150 μm 91% Less than 100 μm 78% Less than 75 μm 71% Less than 45 μm 58.5% Less than 25 μm 47% 2 Bituminous coal from Cape Breton Development Corporation, Nova Scotia, Canada (Harbour Seam)
Seam)) Fixed carbon : 63.5% Volatile components: 34.0% Mineral components: 2.5% The following particle size distribution gives a final composition with a solids content (% by weight of dry article) of up to 78%: <200 μm 100 % Less than 150 μm 91% Less than 100 μm 78% Less than 75 μm 71% Less than 45 μm 58.5% Less than 25 μm 47% In the most typical case, wet milling with a ball mill and/or rod mill is used for the first milling step. This does not limit the use of other conventional pulverization types which can be chosen depending on the characteristic pulverization characteristics of each type of coal and are known to those skilled in the art. A mill circulation path equipped with one or several mills and a classifier is connected to 1 to 3 as described above.
Design so that the following conditions are met. Since it is only in exceptional cases that a suitable particle size distribution can be achieved by passing through one or several mills of the same shape, the comminution circuit must be specially designed to achieve a suitable particle size distribution. must be designed. In most cases, the best results are obtained with mill circuits that are based on a division into various parts, thereby avoiding the deposition of particular grain sizes according to the natural tendency of the coal. One of the difficulties encountered in these milling operations is that these particle size distributions become too narrow due to the concentration of particles in the intermediate range, which means that the volume concentration of the solid material is not sufficient. It means enough. This can be improved, for example, by designing the mill circulation path as follows. Coal is put into a ball mill for wet pulverization along with water. The milled product from the first milling step, which is coarser in particle size than the final product, is introduced into a sieve that is capable of passing only material whose particle size is below the desired maximum size. The coarse material that does not pass through the sieve is
Transfer to a ball mill where the particle size is reduced to increase the fineness of the final product. A hydrocyclone located after the ball mill separates the pulverized product from the ball mill into fine and coarse portions and recirculates the coarse material to the ball mill. The fine portion is recycled to the sieve, which yields a final product having a maximum size determined by the sieve and containing both coarse and fine particles within the desired range. The above example is by no means the only possible explanation of the milling circuit for the first milling step, but merely illustrates how a suitable milled product can be obtained by using conventional milling techniques. It's nothing more than that. Those skilled in the art who are familiar with the above principles valid for particle size and particle size distribution and the properties of the types of coal at their disposal can construct and test operating mill circuits on the basis of known types of mills. The milled product from the first milling step suspended in the aqueous phase can then optionally be directed to a separation process in which the inorganic components are separated from the substantially organic solid fuel components. This separation process typically involves levitating the organic components by taking advantage of their natural buoyant properties and, if this is insufficient, by using flotation agents that increase the buoyancy, such as kerosene or fuel oil. let At the same time, the pyrite can be passivated by adding, for example, FeCl ₃ , calcium ions or other additives that reduce the affinity of the pyrite for gas bubbles. In refining performed in this way, 1 to 5% of the refined coal is produced, depending on the type of coal.
It has been found that coal can be obtained; alternatively, flotation can be carried out in reverse, passivating the coal and removing the inorganic components by flotation with a hydrophobizing additive which selectively renders the inorganic additive hydrophobic. foam flotation in one or more steps comprising: Flotation can also be carried out at some stage between the intermediate milling steps on the intermediate product to release even more inorganic material and increase the degree of final purification. Besides flotation, purification methods include other physical separation methods, such as high-intensity magnetic separation, which can be used for fine particles in the wet phase, and other known purification methods. Flotation results in a certain change in particle size distribution compared to the milled product from the first milling step. Therefore, for a given flow of refined particles, a second comminution step must be carried out in certain cases primarily to compensate for the loss of the finest particles of the particle mass. The selection of the type of mill is dictated by the need to mill a given portion of the material, typically 5-25% of the total amount, to a given maximum particle size, and such selection is a matter for those skilled in the art to know the desired final particle size distribution. is not difficult. The purified product from the first milling step, or the second milling step if any, has a solids content of about 20-50% by weight;
Usually has a solids content of about 25% by weight. Therefore, the purified product preferably has a content of 1 to 2% of the water content of the final composition.
It must be dehydrated to a unit lower moisture content, 1 to 2% units lower, since the additives used are preferably used in the form of an aqueous solution. Dehydration is usually carried out in two steps: thickening followed by filtration in either a vacuum filter or a filter press. In some cases, a flocculant can be introduced into the thickener, provided that it does not interact with the additives for the composition according to the invention. If very low moisture content, for example, 20% by weight or less, is desired, dewatering can be effected satisfactorily by incorporating a finely ground, sufficiently pure dry coal product. After dehydration, one or more additives containing at least the surface-active compounds according to the invention are added to the filter cake obtained. As mentioned above, the additive is provided in the form of an aqueous solution that is added to the filter cake. The mixing method and equipment are designed so that the mixing is as homogeneous as possible and that the surfaces of the particles are covered as completely as possible by the additive. After dehydration and provision of additives, the composition can be pumped into a storage tank for further transport to the user. The use of the fuel slurry of the present invention is suitable for non-descript transportation and handling applications (wherein the fuel slurry is
For example, for transport by pipeline, the following uses may be mentioned in particular: The fuel slurry can be combusted directly in industrial burners, heating plants, or combined power and heating plants for steam and hot water generation.
The fuel slurry of the present invention can be used in place of the conventional fuels used today, such as oil or coal powder, which provides significant advantages in terms of better fuel economy and handling and transportation. Combustion and gasification of the fuel slurry of the present invention can be carried out in plants operated under pressure, resulting in good fuel savings when the fuel slurry is used in place of oil, and It is easier to handle when used in place of regular solid fuel. Gasification in pressurized reactors of the Texaco type, combustion in pressurized fluidized beds and injection of fuel slurry at the tuyere level of blast furnaces may be cited as examples. Of particular importance to the usefulness of the fuel slurry of the present invention are the following features. The fuel slurry can be atomized. That is, by dispersing the fuel in the burner nozzle or the like, a minimum number of individual particle aggregates is obtained. Such aggregation is particularly alleviated by the special dispersion number according to the invention. Additionally, when the fuel slurry is injected into a pressurized reactor, the slurry can be pumped at high pressure and at high shear rates during injection by various types of spreaders. The fuel slurry has a low moisture content, which is extremely important in the combustion process, and also reduces the moisture content of the fuel.
This is particularly important for gasification for the production of synthesis gas, where significantly higher yields can be obtained since it can be kept significantly lower than 30% by weight. As a result of adding a refining step to the manufacturing process,
The fuel slurry contains only a small amount of inorganic impurities, such as yellow sulfur compounds and other inorganic components. Examples are given below to further illustrate the invention and its advantages, but the invention is not limited thereto. The pulverized carbonaceous material used in these examples was bituminous coal from the eastern United States, and more specifically from United Coal Co., Ltd., located in Virginia, United States.
Companise (Widow Kennedy Seam)
Consisting of bituminous coal from The composition of this coal has already been specified. After wet milling in a rod mill and a ball mill, particles with the particle distribution already mentioned were obtained. The specific surface area of the coal powder was 4.5 m ² /g, which was measured according to the BET method using nitrogen adsorption. Examples 1 to 9 The amounts of each additive as shown in Table 1 were dissolved in 30 ml of water having a hardness of 1.2° dh, and then 70 g of coal powder was added and stirred for 1 minute with a glass rod. The appearance of the suspension was then judged according to a scale of 1-4. Where: 1 = dry ("solid") 2 = viscous, poor pumpability 3 = liquid, suitable for pumping 4 = easily flows, excellent pumpability. The suspension was then kept in a sealed beaker for 48 hours and then specifically examined for sedimentation stability. In Table 1, Examples 1-9 relate to the coal slurry of the present invention, while Tests A-G are comparative examples. The examples clearly demonstrate the effect obtained when the ethylene oxide chain contains the number of repeating units defined in the invention.

[Table] Shows 〓.
Coal slurries having the compositions shown in the table below were made by the same method and using the same coal as Examples 1-9. Maintain these slurries for 48 hours,
Thereafter, the slurry was tested in the same manner as in Examples 1-9. The obtained composition and results are shown below.

[TABLE] Examples 10-14 A bituminous high-volatile coal finely ground to minus 200 micron dimensions (e.g. Cape Breton Development Corporation, Sydney, Nova Scotia), water and the ingredients in Table 2. A slurry was prepared from dinonylphenol ethylene oxide adduct. Coal: 71.6% by weight Water: 28.0% by weight Additives: 0.4% by weight The viscosity of the slurry was measured on a Contrave Rheomat 115 at a reverse quadratic shear rate of 451. Results were evaluated and graded on a scale of 1-4. Where: exhibits a viscosity greater than 1600 centipoise exhibits a viscosity of 2500 to 600 centipoise exhibits a viscosity of 3400 to 500 centipoise exhibits a viscosity of less than or equal to 4400 centipoise.

[Table] Petroleum coke finely ground to minus 200μm,
A slurry was prepared from water and an additive obtained from 1 mole of dinonylphenol + 80 moles of ethylene oxide in the amounts shown below. Coke 74.1% by weight Additives 0.85% by weight Water remainder The viscosity of the slurry measured at a shear rate of 451S ^-1 (accelerated layer) on Contrab Rheomats 115 is 440
It was hot.