JPH0113519B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a thinner for coal-water slurries.
More particularly, it relates to a thinning agent for dispersing pulverized coal in water to provide a highly concentrated coal-water slurry that can be pumped. In recent years, due to the depletion of petroleum resources, the use of coal has been reconsidered, and various methods of its use are being considered. However, unlike oil, coal is a solid and cannot be transported by pump. For this reason, various methods are being considered for pulverizing coal and dispersing it in water to form a water slurry. However, with current technology, this method
As the coal concentration increases, it becomes significantly thicker and loses its fluidity, making pumping difficult.
On the other hand, if the coal concentration is lowered, transportation efficiency will decrease, and a dehydration process will become necessary before combustion, which will be expensive and impractical. JP-A No. 54-33803 describes the addition of a polymeric surfactant to a fine ore slurry, but specifically polyacrylamide and polyethyleneimine are only exemplified, and the concentration is low. The target is fine ore slurry. The present inventors have conducted intensive research on a thinning agent for coal-water slurry that fluidizes highly concentrated coal-water slurry and enables pump transportation. , a polyether compound having a specific molecular weight with alkylene oxide added thereto, and a sulfuric acid ester or phosphoric acid ester of the polyether compound have excellent effects, and therefore, the viscosity of coal-water slurry can be reduced by adding a small amount. We have successfully developed a thinning agent that significantly reduces viscosity, thereby providing a pumpable coal-water slurry even at high coal concentrations. By using the thinning agent of the present invention, coal can be fluidized with a small amount of water, making it possible to not only transport it by pump, but also to burn it in a boiler as it is.
The dehydration step before combustion can also be omitted. By using the thinning agent of the present invention, handling of coal becomes extremely simple, and its applications are greatly expanded. The coal used in the coal-water slurry is anthracite;
Any coal may be used, such as bituminous coal, sub-bituminous coal, brown coal, or cleaned versions thereof. Furthermore, the particle size of the coal in the water slurry may be any particle size as long as it is powder, but since the pulverized coal currently burned in thermal power plants has a 200 mesh 70% pass or higher, this particle size is fine. This is a guideline for the particle size of charcoal. However, the thinner of the present invention is not affected by particle size and exhibits excellent effects on coal powder of any particle size. In addition, the cleaned coal contains more inorganic substances than in the coal.
For example, ash and sulfur have been removed. Methods for cleaning coal include, for example, heavy liquid separation method, oil agglomeration method (hereinafter referred to as OA method), and coal flotation method. However, methods other than these may also be used and are not particularly limited. Regarding the OA method, coal is ground by dry or wet grinding, then a water slurry is prepared and an appropriate amount of oil is added, or coal is coated with oil in advance, a water slurry is prepared and stirred. Utilizing the difference in wettability of the organic and inorganic components of coal to oil and water, the organic components of coal are coagulated using oil that selectively wets the organic components of coal as a binder. On the other hand, inorganic substances have a weak affinity with oil, so
Since it is liberated in water, this method can remove inorganic substances at the same time by separating the water from coagulated coal. The coal concentration in the coal-water slurry of the OA method is usually 10-65%. The oil used in the OA method is generally crude oil or various fractions obtained from crude oil, such as kerosene, light oil, A heavy oil, B heavy oil, C heavy oil, etc., tar or shale oil, ethylene cracked residual oil, or various blended oils. The oils used are mineral oils such as lubricating oils and cleaning oils. Water-insoluble oils such as benzene, toluene, xylene, and animal and vegetable oils may also be used, but heavy oils such as C heavy oil and tar residue oil are particularly preferred because they are inexpensive. This oil is generally sufficient in an amount of 30% or less of the coal in the coal-water slurry to be treated for mineral removal. The flotation coal washing method is an existing coal washing method in which a very small amount of oil is added to a pulverized coal-water slurry and stirred to create froth. This method also
Similar to the OA method, the organic components of the coal adhere to the froth oil film, but the inorganic components are released into the water and can be separated from the organic components of the coal. The oils used in the flotation method are turpine oil, tar, A heavy oil, C heavy oil, light oil, and kerosene. Generally, several tens of percent or more of inorganic substances are removed from coal by the above method. The thinning agent for coal-water slurries of the present invention uses a polyalkylene imine having 7 to 200 nitrogen atoms, preferably 9 to 100 nitrogen atoms as a starting material, and adds alkylene oxide to this to increase the molecular weight to 6000 to 100. 60
10,000, preferably 10,000 to 300,000, or a sulfuric acid ester or phosphoric acid ester thereof. The polyether or its sulfuric acid ester or phosphoric acid ester contains ethylene oxide as the alkylene oxide, and the content thereof is 10 to 95% by weight, preferably 30 to 90% by weight of the total added alkylene oxide. It has a great effect. The alkylene oxide added thereto includes ethylene oxide, propylene oxide, butylene oxide, etc. Preferably, propylene oxide and ethylene oxide are copolymerized. In the case of copolymerization, block copolymerization or random copolymerization may be used, or any of the above may be added first, but in order to effectively utilize the surfactant, block copolymerization is more preferable. The alkylene oxide is added at such a rate that the molecular weight of the resulting polyether compound is from 6,000 to 600,000, preferably from 10,000 to 300,000. Also effective are anionic surfactants obtained by converting the above-mentioned polyethers into sulfuric acid esters or phosphoric acid esters. That is, the above-mentioned polyether contains at least one OH group in the molecule and easily reacts with, for example, sulfuric acid, fuming sulfuric acid, chlorosulfonic acid, acidic sodium sulfate, etc., and can introduce a sulfate ester group into the molecule. The OH groups can be esterified in whole or in part. Further, the OH group of the above polyether is, for example, phosphorus pentoxide, metaphosphoric acid,
It can be reacted with thiophosphate and the like to form a phosphoric acid ester. In this case too, all or part of the OH groups can be esterified. The sulfuric acid ester or phosphoric acid ester of the above-mentioned polyether can be used as the thinning agent of the present invention in the form of an acid or in the form of a salt. As cations that form salts, metals such as sodium, potassium, calcium, and magnesium, ammonium, amines, and quaternized amines are useful. Salts include basic salts, neutral salts, and acidic salts. The thinners of this invention are more effective than alkylene oxide adducts of fatty amines, which are relatively similar in structure. The polyalkylene imine starting material for the alkylene oxide adducts of this invention has highly branched branches with a primary amino group at each end and an average of about 2 secondary amino groups per 3 nitrogen atoms in the chain. A polyalkyleneimine having one tertiary amino group and therefore having 7 to 200 nitrogen atoms has a large number of active hydrogen atoms to which alkylene oxide can be added at the ends of each branched branch and in the chain. On the other hand, aliphatic amines such as higher alkyl amines, alkylene diamines, and polyalkylene polyamines have linear structures and have a limited number of active hydrogens. Therefore, alkylene oxide adducts of polyalkyleneimines have very bulky molecular structures, whereas alkylene oxide adducts of alkylamines, alkylene diamines, polyalkylene polyamines, etc. have linear molecular structures. It is certain that such structural features contribute to the excellent effects of the thinner of the present invention. As the thinner according to the present invention, only a polyether having a specific molecular weight or an esterified product thereof, which is obtained by adding an alkylene oxide to a polyalkylene imine having a certain number of nitrogen atoms as a starting material, is effective. In addition, if you use clean coal that has been deashed, the effect will further increase.
This is because the thinner of the present invention effectively acts on the coal surface, which has improved organicity, by removing ash that is highly hydrophilic and has fine particles with a large surface area through deashing. This makes it possible to increase the coal concentration. The thinning agent of the present invention exhibits excellent effects when added in an amount of 0.01 to 5.0% by weight, preferably 0.03 to 2.0% by weight, based on the coal-water slurry. The fluidity limit of a coal-water slurry differs depending on the type and particle size of the coal, but generally, if a thinner is not added, fluidity will disappear at around 50% coal concentration, but with the thinner of the present invention, When added, the viscosity decreases significantly, so it has fluidity even when the coal concentration is 61% or more, especially 70% or more. If cleaner coal is used, the coal concentration will increase by several points, typically 3 to 10 points. The thinner of the present invention can also be used in combination with other surfactants. Regarding the method of producing coal-water slurry and the method of adding a thinner, there are two methods: dry-pulverizing the coal in advance and then mixing the thinner into an aqueous solution, or adding the thinner after making the coal-water slurry. A method of adding coal, water, and a thinner to a mill and mixing it while crushing the coal, and a method of mixing using cleaned coal instead of coal in each method. can be implemented. The thinner of the present invention has an excellent effect of stably dispersing coal in water, and does not cause water separation even when left standing for a long period of time, for example, one month, and maintains a homogeneous coal-water slurry. There is. Thus, the thinner of the present invention can be used in an amount of 0.01 to 5.0% by weight, preferably 0.03 to 5.0% by weight, based on the coal-water slurry.
By adding only 2.0% by weight, the viscosity of the coal-water slurry can be significantly reduced and a highly concentrated coal-water slurry can be produced that can be pumped. Examples are shown below. In the examples, percentages are by weight. Example 1 Coal pulverized to 80% pass of 200 mesh was added to an aqueous solution containing bituminous coal and the thinner shown in Table 1 with stirring at room temperature to prepare a coal-water slurry of a predetermined concentration. The prepared slurry was evaluated by the test method shown below. (1) Slurry viscosity: Measured at 25°C using a Haake rotational viscometer at a shear rate of 100 sec ^-1 . (2) Slurry stability: 300 in a 500ml cylinder
Add the slurry and let it stand for one month, then measure the state of water separation. (3) Slurry life: Measured by pot method. That is, the prepared slurry was placed in a 250 ml wide-mouth bottle, left to stand for one month, and then drained from the bottle by gravity and passed through a 5 mm sieve. At this time, the amount of slurry remaining in the bottle and the amount of slurry on the 5 mm sieve was measured as the amount of agglomeration, and the aggregation rate (%) with respect to the total slurry was determined. The viscosity of the slurry after being left standing for one month was also determined. A slurry with a small amount of agglomeration, a low viscosity, and a viscosity close to that immediately after production is a good slurry with a long life. The evaluation results are shown in Table 2. As is clear from Table 2, when the thinner of the present invention is added, the viscosity decreases even at coal concentrations of 72 to 77%.
1,200 to 2,700 cp, the aggregates can be suppressed to 10% or less even after standing for one month, the viscosity hardly increases, and a highly concentrated coal-water slurry with low viscosity and long life can be obtained. was completed. On the other hand, even when using an alkylene oxide adduct of aliphatic amine other than the product of the present invention, the coal concentration was 72 to 77%.
I was able to obtain slurry of 1700~2800cp, but
The viscosity after standing for one month is about
It has increased by about 1000 cp, and the amount of aggregates has also increased by 20-40%. Example 2 A coal-water slurry was prepared according to Example 1 using cleaned coal. The additives shown in Table 1 were used. The evaluation results are shown in Table 3. As is clear from Table 3, when the thinner of the present invention is added, the viscosity decreases from 1100 to 1100 even when the coal concentration is 77 to 80%.
1800 cp, has extremely good fluidity, and even after standing for one month, aggregates can be kept to less than 10%, and the viscosity hardly increases, making it a highly concentrated coal-water product with low viscosity and long life. I was able to get slurry. On the other hand, even if alkylene oxide adducts of aliphatic amines other than those of the present invention are used, the coal concentration is 78 to 80%.
I was able to obtain a slurry of 1300~2000cp, but
The viscosity after standing for one month is about 30% compared to that immediately after manufacturing
It has increased by about 1000 cp, and the amount of aggregates has also increased by 20-40%.

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Claims (1)

[Claims] 1. Highly concentrated coal used to reduce the viscosity of coal-water slurry and improve fluidity and stability.
A thinning agent for water slurry, with a nitrogen atom number of 7 or more
A polyether compound starting from a polyalkylene imine having 200 atoms, preferably 9 to 100 atoms, and having a molecular weight of 6,000 to 600,000, preferably 10,000 to 300,000 by adding alkylene oxide to this, or the polyether A high-performance thinner for coal-water slurry, characterized by containing a sulfuric acid ester or phosphoric acid ester of a compound as an essential component. 2. The polyether compound or the sulfuric acid ester or phosphoric acid ester of the polyether compound contains ethylene oxide as the alkylene oxide, and the content thereof is 10 to 95% by weight, preferably 30 to 90% by weight of the added alkylene oxide. A high performance thinner for coal-water slurry according to claim 1. 3. The thinning agent for coal-water slurry according to claim 1 or 2, for use in a coal-water slurry having a coal concentration of 61% or higher, preferably higher than 70%. 4. The thinner for coal-water slurry according to claim 1, 2, or 3, wherein the coal is cleaned coal.