CN1062754A - The preparation method of high-concentration coal-water slurry - Google Patents

Abstract

(1) with crusher raw coal being crushed to median size is 300-800 μ, in this broken coal, add entry and dispersion agent, and to grind this mixture with ball mill or rod mill be the high-concentration coal-water slurry of 20-60 μ with the median size that obtains a kind of wherein coal particle.(2) part of grinding said high-concentration coal-water slurry with tower shredder is the high-concentration coal-water slurry of 5-10 μ with the median size that obtains a kind of wherein coal particle.(3) under the condition that has shearing force to exist, the coal-water syrup liquid that obtains in step (2) of the coal-water syrup liquid and 10-40% (weight) that obtains in step (1) of 90-60% (weight) is mixed.Reduced the porosity of slurries like this and produced a kind of low viscosity, the coal-water syrup liquid of high density.

Description

The preparation method of high-concentration coal-water slurry

The present invention relates to the preparation method of high-concentration coal-water slurry.

For transportability, the storage property of improving coal and be easy to processing, the method that adopts is coal grinding is become fine powder and to be scattered in the water with the form of slurries usually.This coal-water syrup liquid is a kind of directly burnt fuel, but considers that from efficiency of combustion this coal-water syrup liquid should have high density, and from being easy to transportation and processing and consider that this coal-water syrup liquid should have low viscosity.In order to solve this conflicting demand of high density and low viscosity, various methods have been attempted up to now.

As the wet type preparation method of high-concentration coal-water slurry, known have a kind of high density Ginding process, in the method, grinds together by broken coal, water and the dispersion agent of ball mill with relatively large amount.Then with thick particle removal, known also have a kind of lower concentration Ginding process, in the method, by ball milling more a spot of relatively broken coal and water are ground together, with the concentration that obtains a kind of wherein coal less than 60%(weight) lower concentration coal-water syrup liquid, again with this slurry dried to form the exsiccant cake, at last the exsiccant cake is scattered in the water to obtain the coal-water syrup liquid of high density.

Past mainly is to use the lower concentration Ginding process, because it removes thick particle by classification easily.For example, coal and water are added in the first step ball mill to produce the coal-water syrup liquid of lower concentration, this slurries dilute with water and sieve to remove thick particle, be dried with moisture eliminator and obtain dried cake, this dried cake is joined in the ball mill of the second stage to obtain high-concentration coal-water slurry (Japanese Patent Application Publication 63-15893//1988) together with water and dispersion agent, perhaps broken coal and water are handled to obtain the lower concentration slurries by tuber grinder, these slurries are divided into two parts, a classified and remove big particle, then be dried to obtain fine grain dried cake, another part handled by the wet type super grinder, mixes with above-mentioned dried cake then and obtains high-concentration coal-water slurry (Japanese Patent Application Publication 63-51493/1988).

Yet these methods all have shortcoming, be difficult to obtain the product of all being satisfied with aspect high density and the lower concentration two exactly, and they comprise complicated operations and need use moisture eliminator.In order to overcome the shortcoming of prior art, main purpose of the present invention provides a kind of method that is used to prepare the high-level efficiency less energy-consumption of stable, high density, low viscosity coal-water syrup liquid.

Be conceived to such fact, be that high density and low viscosity coal-water syrup liquid depend on the intergranular hole ratio of duff in the slurries, it is porosity, and lower porosity can provide higher concentration and more low viscous coal-water syrup liquid, and the inventor has studied the relation between fine grain size distribution of coal and the porosity.

The result, found the method that reduces porosity, promptly the coarse particles coal-water syrup liquid that will contain big particle diameter under the condition that has shearing force to exist mixes with the fine particulate coal-aqueous slurry that contains small particle size, in the case, porosity changes with coarse grained particle diameter, fine grain particle diameter and ratio of mixture, and containing this fine grain high-concentration coal-water slurry can make with tower shredder, has finished the present invention thus.

According to the present invention, a kind of preparation method of high-concentration coal-water slurry is provided, this method comprises that with crusher raw coal being crushed to median size is 300～800 μ, adding entry and dispersion agent in this broken coal and grinding this mixture with ball mill or rod mill is that the concentration of 20～60 μ and coal is 60～80%(weight with the median size that obtains coal) high-concentration coal-water slurry, and the part of the high-concentration coal-water slurry that will obtain is thus ground with tower shredder, with the median size that obtains a kind of coal is that the concentration of 5～10 μ and coal is 60～80%(weight) high-concentration coal-water slurry, and under shearing force with 10～40%(weight) slurries and 90～60%(weight of grinding) the slurries of pulverizing with ball mill or rod mill mix, reduce porosity whereby.

Schema below with reference to the expression embodiment of the invention is at length explained the present invention.In Fig. 1,1 expression raw coal, 2 expression raw coal loading hoppers, 3 expression crushers, 4 expression broken coal loading hoppers, 5 expression constant speed stokers, the water that 6 expressions add, a kind of additive of 7 expressions, 8 expression ball mill or rod mills, 9 expression receiving tanks, 10 expression recirculation slurries, the tower shredder of 11 expressions, 12 expression receiving tanks, 13 expression mixing tanks, and 14 expression products.F represents under meter, and P represents pump.

At first raw coal 1 is added in the crusher 3, this crusher for example is a kind of hammer mill or impact crusher, and it is 300～800 μ that raw coal is crushed to median size.With this broken coal from broken coal loading hopper 4 by constant speed stoker 5 with the water that need to add and dispersion agent 7(anion surfactant for example) add ball mill or the rod mill 8.In ball mill or rod mill 8, coal particle is milled to the particle diameter of 20～60 μ, is 60～80%(weight to obtain a kind of coal concentration) high-concentration coal-water slurry.

The slurries of discharging from ball mill or rod mill 8 are stored in the receiving tank 9, are that 10 that part of returning in ball mill or the rod mill 8 carried out recirculation with numeral.The quantity of recirculation is preferably 10～50%(weight of the slurries of discharging from ball mill or rod mill 8).By this recirculation, because the slurries of discharging from ball mill or rod mill contain fine particle, these fine particles are mixed together with coarse particles in ball mill or rod mill 8, so just reduced particulate porosity in ball mill or rod mill 8, the result has just reduced viscosity, improve flowability, and therefore improved the running of ball mill.This has caused grinding smoothly and having reduced energy consumption.

The part of the high-concentration coal-water slurry in the receiving tank 9 is delivered in the mixing tank 13.Another part of high-concentration coal-water slurry in the receiving tank 9 is delivered in the tower shredder 11.For example, a kind of of this tower shredder is to sell with the trade(brand)name of TOWER MILL.This tower shredder heart position therein is equipped with water screw at a slow speed, and ball and raw material are packed in this tower shredder together.When raw material is ground when moving by the water screw rotation.By tower shredder 11 coal particle being ground to median size is 5～10 μ.This tower shredder can be effectively and is used for the grinding of high-concentration coal-water slurry primely.

10～40%(weight) slurries and 90～60%(weight that the tower shredder 11 of process is handled) but only deliver in the mixing tank 13 and also mix therein through the slurries of ball mill rod mill processing.In this mixing, need to use the sort of mixing tank that can produce high shear force, so that the median size that contains in the slurries of being handled by tower shredder 11 is the median size that contains in coal particle and those slurries of being handled by ball mill or rod mill of 5～10 μ is that the coal particle of 20～60 μ mixes equably, to reduce porosity.Preferably in series arrange two or more mixing tanks.The slurries of being discharged by mixing tank have the porosity that has reduced, thereby have significantly reduced viscosity.The slurries classification that this viscosity can have been reduced if desired is to obtain product 14.Like this, can obtain required high density and low viscous coal-water syrup liquid without moisture eliminator.

In the present invention, in the slurries of handling by ball mill or rod mill, the median size of coal particle is 20～60 μ, and in the slurries of further handling through tower shredder, the median size of coal particle is 5～10 μ.Under the condition that shearing force exists, mix the former and 10～40%(weight of these two kinds of slurries (i.e. 90～60%(weight) in predetermined ratio) the latter), can make the porosity reduction and its viscosity is significantly reduced.Come this situation is described in further detail with reference to embodiment below.

Fig. 2 has shown coal-water syrup liquid mixture (coal concentration: ratio of mixture 68.5%) and the relation between the porosity, and the relation between this ratio of mixture and the viscosity, said mixture comprises what a kind of process ball mill or rod mill were handled, its median size is that coal-water syrup liquid and the tower shredder of another kind of further process of 51 μ grinds, and median size is the coal-water syrup liquid of 5.2 μ.Just as shown in the drawing, when the slurries that ground by tower shredder being joined only in the slurries that ball mill or rod mill were handled, porosity reduces along with the increase of said add-on, and viscosity also decreases.But after said add-on surpassed about 20%, porosity then increased and viscosity sharply increases.Therefore, when using these two kinds of slurries, 20% slurries and 80% slurries through ball mill or rod mill processing of handling through tower shredder are mixed the coal-water syrup liquid that can obtain high density with different median sizes.It also is like this that the slurries of gained have under the situation of the low viscosity that is lower than 800CP (even in coal concentration up to 68.5%(weight)) and satisfactory stability.

Fig. 3 has shown the ratio of mixture of coal-water syrup liquid mixture (concentration of coal is 67.1%) and the relation between the relation between the porosity and this ratio of mixture and the viscosity, said mixture comprises what a kind of process ball mill or rod mill were handled, its median size is that coal-water syrup liquid and the tower shredder of another kind of further process of 40 μ grinds, and its median size is the coal-water syrup liquid of 8.4 μ.In this case, use 75%(weight) slurries and 25%(weight only handled through ball mill or rod mill) slurries further handled through tower shredder mix, and can obtain the porosity of minimum and be about the minimal viscosity of 500CP.

As mentioned above, the slurries of only handling through ball mill or rod mill will depend on their median sizes separately with the blending ratio of the slurries of further handling through tower shredder.Therefore, need only median size and the ratio of mixture suitably adjusted separately, can easily obtain high density, low viscosity and stable coal-water syrup liquid.

With crusher (as impact crusher etc.) with coal when broken, along with the reduction of particle diameter, required energy is corresponding to be increased, still, the situation for only median size being reduced to about 300 μ does not then need very high energy.Yet, be 300 μ or littler if be crushed to median size, need very high energy.For coal being crushed to median size is 300 μ or littler, uses ball mill or rod mill just to have the advantage of relatively low energy consumption.In addition, in the shattering process of ball mill or rod mill, be 20 μ or littler in order to be crushed to median size, then can cause required energy to increase rapidly.Be about 20 μ or littler for coal being crushed to median size, use tower shredder just to have the advantage of relatively low energy consumption.In the present invention, using crusher (as impact crusher etc.) that coal is crushed to median size is 300～800 μ, with ball mill or rod mill coal being crushed to median size is 20～60 μ, is 5～10 μ with tower shredder with coal grinding to median size, and the purpose of Kao Lving is the required energy consumption of grinding that is used for coal in order to reduce like this.

In the present invention, under the condition that has shearing force to exist, by satisfactory ratio of mixture broken under high density with ball mill or rod mill, the slurries that contain median size and be the coal of 20～60 μ are that the slurries of the coal particle of 5～10 μ mix with the median size that contains of grinding under high density with tower shredder, obtain a kind of minimum porosity that has thus, high density, low viscosity and stable coal-water syrup liquid.In addition, owing to carry out fragmentation and grinding under high density, so the present invention can save the drying process to slurries, and reduced energy consumption and simplified operation.Have, the present invention combines use to crusher and shredder according to the diameter of coal particle again, has further reduced energy consumption whereby.

Claims (2)

1, a kind of preparation method of high-concentration coal-water slurry, this method comprises that with crusher raw coal being crushed to median size is 300～800 μ, in this broken coal, add entry and dispersion agent, and to grind this mixture with ball mill or rod mill be that 20～60 μ and coal concentration are the high-concentration coal-water slurry of 60～80% (weight) to obtain a kind of coal particle median size, a part of grinding the high-concentration coal-water slurry that is obtained with tower shredder is that 5～10 μ and coal concentration are the high-concentration coal-water slurry of 60～80% (weight) to obtain a kind of wherein coal particle median size, under the condition that has shearing force to exist, the said slurries that only pass through ball mill or rod mill fragmentation of the slurries and 90～60% (weight) of the described grinding of 10～40% (weight) are mixed then, to reduce said porosity.

2, according to the process of claim 1 wherein 10～50%(weight) the described slurries by discharging in ball mill or the rod mill return again in ball mill or the rod mill to carry out recirculation.

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