CA1125534A - Process for producing potassium silicate fertilizer and apparatus for practicing said process - Google Patents
Process for producing potassium silicate fertilizer and apparatus for practicing said processInfo
- Publication number
- CA1125534A CA1125534A CA337,070A CA337070A CA1125534A CA 1125534 A CA1125534 A CA 1125534A CA 337070 A CA337070 A CA 337070A CA 1125534 A CA1125534 A CA 1125534A
- Authority
- CA
- Canada
- Prior art keywords
- fluidized
- product
- waste gas
- process according
- dryer
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 238000000034 method Methods 0.000 title claims abstract description 34
- 239000004111 Potassium silicate Substances 0.000 title claims abstract description 17
- 239000003337 fertilizer Substances 0.000 title claims abstract description 17
- 235000019353 potassium silicate Nutrition 0.000 title claims abstract description 17
- NNHHDJVEYQHLHG-UHFFFAOYSA-N potassium silicate Chemical compound [K+].[K+].[O-][Si]([O-])=O NNHHDJVEYQHLHG-UHFFFAOYSA-N 0.000 title claims abstract description 17
- 229910052913 potassium silicate Inorganic materials 0.000 title claims abstract description 17
- KRKNYBCHXYNGOX-UHFFFAOYSA-N citric acid Chemical compound OC(=O)CC(O)(C(O)=O)CC(O)=O KRKNYBCHXYNGOX-UHFFFAOYSA-N 0.000 claims abstract description 66
- 238000001354 calcination Methods 0.000 claims abstract description 48
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 claims abstract description 30
- 239000012530 fluid Substances 0.000 claims abstract description 29
- 239000000203 mixture Substances 0.000 claims abstract description 27
- ZLMJMSJWJFRBEC-UHFFFAOYSA-N Potassium Chemical compound [K] ZLMJMSJWJFRBEC-UHFFFAOYSA-N 0.000 claims abstract description 21
- 238000001035 drying Methods 0.000 claims abstract description 21
- 239000010881 fly ash Substances 0.000 claims abstract description 21
- 239000011591 potassium Substances 0.000 claims abstract description 21
- 229910052700 potassium Inorganic materials 0.000 claims abstract description 21
- 238000001816 cooling Methods 0.000 claims abstract description 17
- BWHMMNNQKKPAPP-UHFFFAOYSA-L potassium carbonate Chemical compound [K+].[K+].[O-]C([O-])=O BWHMMNNQKKPAPP-UHFFFAOYSA-L 0.000 claims abstract description 15
- 239000011230 binding agent Substances 0.000 claims abstract description 10
- 239000003245 coal Substances 0.000 claims abstract description 10
- 235000011118 potassium hydroxide Nutrition 0.000 claims abstract description 10
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims abstract description 8
- 229910052710 silicon Inorganic materials 0.000 claims abstract description 8
- 239000010703 silicon Substances 0.000 claims abstract description 8
- 238000004898 kneading Methods 0.000 claims abstract description 7
- 229910000027 potassium carbonate Inorganic materials 0.000 claims abstract description 7
- 235000011181 potassium carbonates Nutrition 0.000 claims abstract description 6
- 239000002912 waste gas Substances 0.000 claims description 32
- 239000000428 dust Substances 0.000 claims description 24
- 239000008187 granular material Substances 0.000 claims description 24
- 239000002918 waste heat Substances 0.000 claims description 10
- 206010037660 Pyrexia Diseases 0.000 claims description 7
- 239000007789 gas Substances 0.000 claims description 7
- 239000000843 powder Substances 0.000 claims description 6
- VTHJTEIRLNZDEV-UHFFFAOYSA-L magnesium dihydroxide Chemical compound [OH-].[OH-].[Mg+2] VTHJTEIRLNZDEV-UHFFFAOYSA-L 0.000 claims description 4
- 239000000347 magnesium hydroxide Substances 0.000 claims description 4
- 229910001862 magnesium hydroxide Inorganic materials 0.000 claims description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 4
- 238000010298 pulverizing process Methods 0.000 claims description 3
- 239000000126 substance Substances 0.000 claims description 3
- 239000003232 water-soluble binding agent Substances 0.000 claims description 3
- 239000000295 fuel oil Substances 0.000 claims description 2
- 238000004064 recycling Methods 0.000 claims description 2
- 238000004806 packaging method and process Methods 0.000 claims 2
- 238000006243 chemical reaction Methods 0.000 abstract description 3
- 239000007858 starting material Substances 0.000 abstract description 3
- 238000009740 moulding (composite fabrication) Methods 0.000 abstract 1
- 239000000047 product Substances 0.000 description 31
- 229960003975 potassium Drugs 0.000 description 16
- 235000007686 potassium Nutrition 0.000 description 16
- 229940074415 potassium silicate Drugs 0.000 description 10
- 239000000463 material Substances 0.000 description 6
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 4
- 241000196324 Embryophyta Species 0.000 description 3
- 235000012239 silicon dioxide Nutrition 0.000 description 3
- 239000002253 acid Substances 0.000 description 2
- 229910052681 coesite Inorganic materials 0.000 description 2
- 229910052906 cristobalite Inorganic materials 0.000 description 2
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 2
- 239000000377 silicon dioxide Substances 0.000 description 2
- 239000002689 soil Substances 0.000 description 2
- 229910052682 stishovite Inorganic materials 0.000 description 2
- 229910052905 tridymite Inorganic materials 0.000 description 2
- BPQQTUXANYXVAA-UHFFFAOYSA-N Orthosilicate Chemical compound [O-][Si]([O-])([O-])[O-] BPQQTUXANYXVAA-UHFFFAOYSA-N 0.000 description 1
- BFNBIHQBYMNNAN-UHFFFAOYSA-N ammonium sulfate Chemical compound N.N.OS(O)(=O)=O BFNBIHQBYMNNAN-UHFFFAOYSA-N 0.000 description 1
- 229910052921 ammonium sulfate Inorganic materials 0.000 description 1
- 235000011130 ammonium sulphate Nutrition 0.000 description 1
- 239000002956 ash Substances 0.000 description 1
- 239000012467 final product Substances 0.000 description 1
- -1 i.e. Substances 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000003345 natural gas Substances 0.000 description 1
- 230000020477 pH reduction Effects 0.000 description 1
- 235000015320 potassium carbonate Nutrition 0.000 description 1
- RMAQACBXLXPBSY-UHFFFAOYSA-N silicic acid Chemical compound O[Si](O)(O)O RMAQACBXLXPBSY-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C05—FERTILISERS; MANUFACTURE THEREOF
- C05D—INORGANIC FERTILISERS NOT COVERED BY SUBCLASSES C05B, C05C; FERTILISERS PRODUCING CARBON DIOXIDE
- C05D1/00—Fertilisers containing potassium
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B33/00—Silicon; Compounds thereof
- C01B33/20—Silicates
- C01B33/32—Alkali metal silicates
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P20/00—Technologies relating to chemical industry
- Y02P20/10—Process efficiency
- Y02P20/129—Energy recovery, e.g. by cogeneration, H2recovery or pressure recovery turbines
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Processing Of Solid Wastes (AREA)
- Fertilizers (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
A process for producing a citric acid soluble potassium silicate fertilizer comprises a step for kneading a mixture con-sisting essentially of potassium carbonate, fly ash, pulverized coal, other necessary starting materials and a caustic potash solution as a binder and then granulating the kneaded mixture, a step for drying the granulated product to a nearly absolutely dry state, and a step for calcining the dried granular product, whereby a chemical reaction takes place between the potassium and the silicon present in fly ash to convert them into a citric acid soluble potassium silicate. An apparatus for practicing the processes mentioned above comprises a plurality of continuous quantitat? ??s, a continuous kneader, an extruder for form-ing ??? ? fluid dryer, a fluid calcining furnace, and a cooling device for cooling calcined product.
A process for producing a citric acid soluble potassium silicate fertilizer comprises a step for kneading a mixture con-sisting essentially of potassium carbonate, fly ash, pulverized coal, other necessary starting materials and a caustic potash solution as a binder and then granulating the kneaded mixture, a step for drying the granulated product to a nearly absolutely dry state, and a step for calcining the dried granular product, whereby a chemical reaction takes place between the potassium and the silicon present in fly ash to convert them into a citric acid soluble potassium silicate. An apparatus for practicing the processes mentioned above comprises a plurality of continuous quantitat? ??s, a continuous kneader, an extruder for form-ing ??? ? fluid dryer, a fluid calcining furnace, and a cooling device for cooling calcined product.
Description
llZS53,4 The present invention relates to a process for pro-ducing citric acid soluble potassium silicate fertilizer in a high yield and with a high heat efficiency, and to an apparatus for use in said process.
As is well known, a citric acid soluble potassium ferti-lizer can be solubilized by the citric acid excreted by the roots of plants, but only a certain amount of the fertilizer is solu-bilized and absorbed into the plant. Unlike the usual water-soluble potassium fertilizers, the citric acid soluble potassium fertilizer is resistant to rain water. Further, it neutralizes acid in soil caused by the citric acid excreted by plant roots.
Although such a citric acid soluble potassium fertilizer is suitable for Japanese agriculture where the climate is relatively warm and rainy and the acidification of soil is already at an advanced stage due to the use of chemical fertilizers, such as ammonium sulfate, its practical use is only rare. This is mainly attributableto the fact that if a citric acid soluble potassium silicate fertilizer is produced by the conventional process from fly ash as a silicic acid source, a continuous operation is quite difficult to conduct because of the high temperature necessary for calcination, which inevitably results in high cost as compared with other fertilizers. In addition, such fertilizers produced using known techniques lack uniform product quality.
Earnest studies have been conducted with the aim of overcoming the above-mentioned difficulties encountered with citric acid soluble potassium fertilizers. As a result, it has been discovered that an inexpensive potassium fertilizer of high quality can be produced with a high efficiency by utilizing fly ash, such as that formed in power stations operated with coal, together with inexpensive crude caustic potash .
Fly ash is contained in waste gases formed in boilers -1- .
and furnaces operated with pulverized coa], such as those in thermal power stations. The fly ash contains a large quantity of silicon. If the fly ash is admixed with a potassium source, such as caustic potash (KOH) or potassium carbonate and calcined at a temperature of about 600 to l,100C, the potassium reacts with the silicon present in fly ash to form a citric acid soluble potassium silicate. The chemical reactions that occur can be expressed by the following chemical equations:
If caustic potash is used as potassium source, 2KOH + SiO2 ~ K2O.SiO2 + H2O
(water-soluble potassium) 2KOH + nSiO2 - ~ K2O.nSiO2 n = 2-6 (citric acid soluble potassium silicate), If potassium carbonate is used as potassium source,
As is well known, a citric acid soluble potassium ferti-lizer can be solubilized by the citric acid excreted by the roots of plants, but only a certain amount of the fertilizer is solu-bilized and absorbed into the plant. Unlike the usual water-soluble potassium fertilizers, the citric acid soluble potassium fertilizer is resistant to rain water. Further, it neutralizes acid in soil caused by the citric acid excreted by plant roots.
Although such a citric acid soluble potassium fertilizer is suitable for Japanese agriculture where the climate is relatively warm and rainy and the acidification of soil is already at an advanced stage due to the use of chemical fertilizers, such as ammonium sulfate, its practical use is only rare. This is mainly attributableto the fact that if a citric acid soluble potassium silicate fertilizer is produced by the conventional process from fly ash as a silicic acid source, a continuous operation is quite difficult to conduct because of the high temperature necessary for calcination, which inevitably results in high cost as compared with other fertilizers. In addition, such fertilizers produced using known techniques lack uniform product quality.
Earnest studies have been conducted with the aim of overcoming the above-mentioned difficulties encountered with citric acid soluble potassium fertilizers. As a result, it has been discovered that an inexpensive potassium fertilizer of high quality can be produced with a high efficiency by utilizing fly ash, such as that formed in power stations operated with coal, together with inexpensive crude caustic potash .
Fly ash is contained in waste gases formed in boilers -1- .
and furnaces operated with pulverized coa], such as those in thermal power stations. The fly ash contains a large quantity of silicon. If the fly ash is admixed with a potassium source, such as caustic potash (KOH) or potassium carbonate and calcined at a temperature of about 600 to l,100C, the potassium reacts with the silicon present in fly ash to form a citric acid soluble potassium silicate. The chemical reactions that occur can be expressed by the following chemical equations:
If caustic potash is used as potassium source, 2KOH + SiO2 ~ K2O.SiO2 + H2O
(water-soluble potassium) 2KOH + nSiO2 - ~ K2O.nSiO2 n = 2-6 (citric acid soluble potassium silicate), If potassium carbonate is used as potassium source,
2 3 io2 ~ K2O.Sio2 + CO2 (water-soluble potassium) K2CO3 + nSiO2 > K2O.nSiO2 n = 2-6 (citric acid soluble potassium silicate) As is well known, fly ash has a size of micron order, so that if one wishes to calcine it, such as by means of a fluid calcining furnace, it scatters in the hot air used as the calcina-tion medium, and the calcination cannot be carried out.
In view of the above, the problems have been earnestly studied, and it has been discovered that calcination can be carried out with high efficiency if the starting materials, such as fly ash, potassium source and other required materials are kneaded with a binder, such as caustic potash solution and then t the kneaded mixture is formed into granules having a size of about 3 to about 5 mm. The granules can then be calcined to form a product that is usually cooled, pulverized, further granu-lated and dried, after which it is shipped as a final product.
1~25~3~
More particularly, the present invention provides a process for producing citric acid so:Luble potassium silicate fre-tilizer, which process comprises:
~ a) forming a mixture comprising a solution of 40 to 50% caustic potash as a binder in an amount of 20 to 25 parts by weight based on the mixture, potassium carbonate in an amount of 9 to 12 parts by weight based on the mixture, fly ash in an amount of 50 to 70 parts by weight based on the mixture and pulverized coal in an amount of 5 to 30 parts by weight based on the mixture;
tb) kneading the mixture by means of a continuous kneader;
(c) forming the resulting kneaded mixture into granules by means of an extruder;
(d) drying said granules to a state of substantially absolute dryness by means of a fluidized dryer; and (e) calcining the resulting dried granules at a tempera-ture fron 900C to 1100C, by means of a fluidized calcining fur-nace in order to chemically react the potassium with silicon pre-sent in the fly ash and thereby form a citric acid soluble potas-sium silicate.
Additionally, this invention provides an apparatus for producing a citric acid soluble potassium silicate fertilizer ac-cording to the processes of this invention, which apparatuscomprises:
(a) a plurality of continuous quantitative feeders for supplying the binder, potassium source, fly ash and pulverized coal for formlng the mixture;
(b) a continuous kneader for contlnuously kneading the mixture;
(c) an extruder for forming the resulting kneaded mixture into granules;
(d) a fluidized dryer for drying the granules to a state of substantlally absolute dryness;
(e) a fluidized calcining furnace for calcining dried ~ranules in o~der to chemically react pot~ssium with silicon present in the ~ly ash and the~eby ~or~ ~ citXic acid soluble - 3a -11~5~3~
potassium silicate; and (f) a cooling device for cooling the resulting calcined product.
In practicing this invention, the pulverized coal gen-erates heat throughout the period during which the kneaded and granulated product is calcined in the fluid calcining furnace, and thereby acts so as to maintain the granular product at a high temperature over a long period of time.
In another embodiment of this invention, the calcined product is cooled by means of a high speed cooling device, and then pulverized into powder by means of a pulverizer, after which it is transferred to a product storage tank.
When the calcined and pulverized product is to be shipped in the form of a powdery product, it can be taken out of the product storage tank by means of a screw feeder and trans-ported to a package station.
When the calcined and pulverized product is to be ship-ped in a granular form, it can be fed by means of a screw feeder into a granulator where it can be kneaded together with an added water-soluble binder, granulated and dried, after which it can be transported to a package station.
In order to prepare a calcined product in a granular form, the apparatus of the invention can additionally be equipped with a pulverizer for pulverizing the calcined and cooled product, a storage tank for storing the pulverized product, a granulator for kneading and granulating the product carried out of the storage tank and a second fluid dryer for drying the granulated product.
Preferably waste gas that is discharged from the first fluid dryer is introduced into a dry dust chamber to remove floating dust, and then the removed floating dust is returned to the continuous kneader.
~lZ5531~
Preferably, waste gas that is discharged from the fluid calcining furnace is introduced into a heat exchanyer, and the waste heat is transmitted to low temperature air from a secondary line. The air heated thereby can then be supplied to the first fluid dryer for use as a drying medium.
Further, it is preferable to supply waste gas discharged from the cooler directly into a second fluid dryer for use as a drying medium.
It is also preferable to introduce waste gas from the second fluid dryer into a dry dust chamber where floating dust present therein is removed. The removed floating dust can then be returned to a product storage tank.
In another embodiment of this invention, there is pro-vided a hot air generating device where natural gas or a fuel oil is burned in order to supply a calcining medium of high tempera-ture to the fluidized calcining furnace used for the calcination of granulated product. Preferably, waste gas discharged from the fluidized calcining furnace is returned to said hot air generat-ing device via a heat exchanger.
It is also preferable that waste heat is waste gas dis-charged from the fluid calcining furnace be transmitted to the low temperature air via the first and second heat exchanger, and the air heated thereby then supplied to the second dryer as a drying medium.
The present invention will be further illustrated by way of the accompanying drawing in which:
Figure 1 is a flow sheet for the production of citric acid soluble silicate fertil'zer according to one embodiment of the present invention.
As shown in the left upper part of the Figure, there are provided quantitative feeders la to lf for continuously measuring and feeding materials. The first continuous quantitative feeder 11255;34 la continuously measures 48% caustic potash (KO~I) and feeds it into continuous kneader 2 via line La-1. Similarly, second feeder lb handles potassium carbonate (K2CO3), third feeder lc handles magnesium hydroxide [Ma(OH)2], fourth feeder ld handles pulverized coal and sixth feeder lf handles fly ash. The fifth feeder le is a reserve. It should be noted that the above-mentioned magnesium hydroxide is not indispensable in the invention but when present is preset in an amount of 3 to 4 parts by weight based on the mixture.
The materials supplied by the continuous quantitative feeders la-lf are kneaded in continuous kneader 2 to give a slime, which passes line La-2 and reaches extruder 3. The slimy material is formed by extruder 3 into granules of about 3 to about 5 mm size, and the granules are then supplied to fluid dryer 4 via line La-3.
Fluid dryer 4 is a fluidized bed type of dryer equipped with a porous plate. One blows hot air, recovered in heat exchan-ger 18 mentioned later, via line Lb-4, whereby granules on the porous plate are fluidized and dried to a state of absolute dry-ness where no water is contained at all. The drying temperature is in the range of about 200 to about 300C, and the drying time is about 10 minutes. This is for the reason that if drying tem-perature is higher than about 300C, there occur cracks in the granule and if it is lower than about 200C an absolute dryness is quite difficult to reach.
Floating dust leaving fluid dryer 4 passes lines Lb-5 and Lc-2 and reaches dry dust chamber 17 where it is recovered.
Recovered material is returned to continuous kneader 2 via line Ld-l. A part of the hot air leaving fluid dryer 4isrecycled to fluiddryer 4 via linesLb-5 andLb-6 with the aid of recycling fan 19.
The granular product, which has been dried to the state of absolute dryness in fluid dryer 4, passes line La-4 and is 11251~34 supplied to fluid calcininy furllace 6 by screw fecder 5. Fluid calcining furnace 6 is a fluidized bed type equipped with a porous plate. The granular product on the porous plate is cal-cined and brought into a fluidized state by the action of hot air, which has been introduced from hot air generator 16 via line Lb-l. Silicon present in fly ash reacts with potassium to form a citric acid soluble potassium silicate. The calcining temperature in fluid calcining furnace 6 is in the range of about 900 to about l,100~C and the time period of calcination is about 15 minutes. This is for the reason that if calcining temperature is lower than about 900C, no reaction takes place. If it is higher than about l,100C, the granules soften to form plate-like matter.
Hot air generator 16 has an adjacent liquefied gas tank 14 from which liquefied gas is fed into hot air generator 16 via line Le by pump 15. The higher temperature waste gas leaving fluid calcining furnace 6 passes line Lb-2 and reaches heat ex-changer 18 where it releases its heat by means of heat exchange, after which it passes line Lb-3 and reaches hot air generator 16 again. On the other hand, air supplied from blower 20 into heat exchanger 18 via line Lc-l and heated there passes line Lb-4 and reaches fluid dryer 4.
The product, which has completely been calcined in fluid calcining furnace 6, passes line La-5 and is sent to high speed cooling device 8 by screw feeder 7. High speed cooling device 8 is a fluidized bed type of cooler equipped with a porous plate.
Cold air supplied by cooling fan 21 via line Lb~7 fluidizes the calcined product and rapidly cools it. Hot air leaving the high speed cooling device 8 passes line Lb-8 and reaches second fluid dryer 13 mentioned later where it is used as a drying medium for fluid dryer 13. The residence time of calcined product in the high speed cooling device 8 is about 10 minutes.
llZS'534 Product cooled in hiyh speed cooling device 8 passes line La-6 and reaches pulverizer 9 where it is pulverized into powder, after which it is transportecl to product storage tank 10 via line La-7. Floating dust leaving product storage tank 10 passes line Lc~3 and is recovered, after which it is returned to pulverizer 9 via Lc-4 by transporting fan 22. The product in storage tank 10 is shipped as a powdery product A-l via screw feeder 11 and line La-8. Otherwise, the product is sent to granu-lator 12 where it is kneaded together with a binder, i.e., water or other water-soluble binder fed from binder tank 23 via line Lf and granulated, after which is passes line La-9, is dried in second fluid dryer 13, passes line La-10 and is then shipped as a granular product A-2. Floating dust leaving second fluid dryer 13 passes line Lc-5, is recovered in dry dust chamber 24, then passes line Ld-2 and is finally recovered in line La-7.
Waste gas leaving dry dust chamber 17 is driven by waste gas gan 25 and passes lines Lc-6 and Lc-8 to be released into the atmosphere from chimney 27, while waste gas leaving dry dust chamber 24 is driven by waste gas fan 26 and passes lines Lc-7 and Lc-9 to be released into the atmosphere via chimney 27.
A concrete example of the above-mentioned process is described below.
Starting materials were measured in continuous quanti-tative feeders la-lf in the following proportions:
0.88 T/H of 45% caustic potash solution as a binder, 0.436 T/H of potassium carbonate, 0.136 T/H of magnesium hydroxide, 0.4 T/H of pulverized coal, and 2.148 T/H of fly ash.
The materials were sent to continuous kneader 2 and kneaded therein. After kneading, the slimy starting mixture was supplied to extruder 3 where it was granulated into cylindrical granules having a diameter of 3 mm and a length of 5 mm.
Then, the granules were sent to fluid dryer 4 where they were dried at 250C for 10 minutes until they reached absolute dryness. Subsequently, the granules were sent to fluid calcining furnace 6 where they were calcined at 1,000C
for 15 minutes. After calcination, the product was sent to high speed cooler 8 where it was cooled with cold air for 15 minutes.
In view of the above, the problems have been earnestly studied, and it has been discovered that calcination can be carried out with high efficiency if the starting materials, such as fly ash, potassium source and other required materials are kneaded with a binder, such as caustic potash solution and then t the kneaded mixture is formed into granules having a size of about 3 to about 5 mm. The granules can then be calcined to form a product that is usually cooled, pulverized, further granu-lated and dried, after which it is shipped as a final product.
1~25~3~
More particularly, the present invention provides a process for producing citric acid so:Luble potassium silicate fre-tilizer, which process comprises:
~ a) forming a mixture comprising a solution of 40 to 50% caustic potash as a binder in an amount of 20 to 25 parts by weight based on the mixture, potassium carbonate in an amount of 9 to 12 parts by weight based on the mixture, fly ash in an amount of 50 to 70 parts by weight based on the mixture and pulverized coal in an amount of 5 to 30 parts by weight based on the mixture;
tb) kneading the mixture by means of a continuous kneader;
(c) forming the resulting kneaded mixture into granules by means of an extruder;
(d) drying said granules to a state of substantially absolute dryness by means of a fluidized dryer; and (e) calcining the resulting dried granules at a tempera-ture fron 900C to 1100C, by means of a fluidized calcining fur-nace in order to chemically react the potassium with silicon pre-sent in the fly ash and thereby form a citric acid soluble potas-sium silicate.
Additionally, this invention provides an apparatus for producing a citric acid soluble potassium silicate fertilizer ac-cording to the processes of this invention, which apparatuscomprises:
(a) a plurality of continuous quantitative feeders for supplying the binder, potassium source, fly ash and pulverized coal for formlng the mixture;
(b) a continuous kneader for contlnuously kneading the mixture;
(c) an extruder for forming the resulting kneaded mixture into granules;
(d) a fluidized dryer for drying the granules to a state of substantlally absolute dryness;
(e) a fluidized calcining furnace for calcining dried ~ranules in o~der to chemically react pot~ssium with silicon present in the ~ly ash and the~eby ~or~ ~ citXic acid soluble - 3a -11~5~3~
potassium silicate; and (f) a cooling device for cooling the resulting calcined product.
In practicing this invention, the pulverized coal gen-erates heat throughout the period during which the kneaded and granulated product is calcined in the fluid calcining furnace, and thereby acts so as to maintain the granular product at a high temperature over a long period of time.
In another embodiment of this invention, the calcined product is cooled by means of a high speed cooling device, and then pulverized into powder by means of a pulverizer, after which it is transferred to a product storage tank.
When the calcined and pulverized product is to be shipped in the form of a powdery product, it can be taken out of the product storage tank by means of a screw feeder and trans-ported to a package station.
When the calcined and pulverized product is to be ship-ped in a granular form, it can be fed by means of a screw feeder into a granulator where it can be kneaded together with an added water-soluble binder, granulated and dried, after which it can be transported to a package station.
In order to prepare a calcined product in a granular form, the apparatus of the invention can additionally be equipped with a pulverizer for pulverizing the calcined and cooled product, a storage tank for storing the pulverized product, a granulator for kneading and granulating the product carried out of the storage tank and a second fluid dryer for drying the granulated product.
Preferably waste gas that is discharged from the first fluid dryer is introduced into a dry dust chamber to remove floating dust, and then the removed floating dust is returned to the continuous kneader.
~lZ5531~
Preferably, waste gas that is discharged from the fluid calcining furnace is introduced into a heat exchanyer, and the waste heat is transmitted to low temperature air from a secondary line. The air heated thereby can then be supplied to the first fluid dryer for use as a drying medium.
Further, it is preferable to supply waste gas discharged from the cooler directly into a second fluid dryer for use as a drying medium.
It is also preferable to introduce waste gas from the second fluid dryer into a dry dust chamber where floating dust present therein is removed. The removed floating dust can then be returned to a product storage tank.
In another embodiment of this invention, there is pro-vided a hot air generating device where natural gas or a fuel oil is burned in order to supply a calcining medium of high tempera-ture to the fluidized calcining furnace used for the calcination of granulated product. Preferably, waste gas discharged from the fluidized calcining furnace is returned to said hot air generat-ing device via a heat exchanger.
It is also preferable that waste heat is waste gas dis-charged from the fluid calcining furnace be transmitted to the low temperature air via the first and second heat exchanger, and the air heated thereby then supplied to the second dryer as a drying medium.
The present invention will be further illustrated by way of the accompanying drawing in which:
Figure 1 is a flow sheet for the production of citric acid soluble silicate fertil'zer according to one embodiment of the present invention.
As shown in the left upper part of the Figure, there are provided quantitative feeders la to lf for continuously measuring and feeding materials. The first continuous quantitative feeder 11255;34 la continuously measures 48% caustic potash (KO~I) and feeds it into continuous kneader 2 via line La-1. Similarly, second feeder lb handles potassium carbonate (K2CO3), third feeder lc handles magnesium hydroxide [Ma(OH)2], fourth feeder ld handles pulverized coal and sixth feeder lf handles fly ash. The fifth feeder le is a reserve. It should be noted that the above-mentioned magnesium hydroxide is not indispensable in the invention but when present is preset in an amount of 3 to 4 parts by weight based on the mixture.
The materials supplied by the continuous quantitative feeders la-lf are kneaded in continuous kneader 2 to give a slime, which passes line La-2 and reaches extruder 3. The slimy material is formed by extruder 3 into granules of about 3 to about 5 mm size, and the granules are then supplied to fluid dryer 4 via line La-3.
Fluid dryer 4 is a fluidized bed type of dryer equipped with a porous plate. One blows hot air, recovered in heat exchan-ger 18 mentioned later, via line Lb-4, whereby granules on the porous plate are fluidized and dried to a state of absolute dry-ness where no water is contained at all. The drying temperature is in the range of about 200 to about 300C, and the drying time is about 10 minutes. This is for the reason that if drying tem-perature is higher than about 300C, there occur cracks in the granule and if it is lower than about 200C an absolute dryness is quite difficult to reach.
Floating dust leaving fluid dryer 4 passes lines Lb-5 and Lc-2 and reaches dry dust chamber 17 where it is recovered.
Recovered material is returned to continuous kneader 2 via line Ld-l. A part of the hot air leaving fluid dryer 4isrecycled to fluiddryer 4 via linesLb-5 andLb-6 with the aid of recycling fan 19.
The granular product, which has been dried to the state of absolute dryness in fluid dryer 4, passes line La-4 and is 11251~34 supplied to fluid calcininy furllace 6 by screw fecder 5. Fluid calcining furnace 6 is a fluidized bed type equipped with a porous plate. The granular product on the porous plate is cal-cined and brought into a fluidized state by the action of hot air, which has been introduced from hot air generator 16 via line Lb-l. Silicon present in fly ash reacts with potassium to form a citric acid soluble potassium silicate. The calcining temperature in fluid calcining furnace 6 is in the range of about 900 to about l,100~C and the time period of calcination is about 15 minutes. This is for the reason that if calcining temperature is lower than about 900C, no reaction takes place. If it is higher than about l,100C, the granules soften to form plate-like matter.
Hot air generator 16 has an adjacent liquefied gas tank 14 from which liquefied gas is fed into hot air generator 16 via line Le by pump 15. The higher temperature waste gas leaving fluid calcining furnace 6 passes line Lb-2 and reaches heat ex-changer 18 where it releases its heat by means of heat exchange, after which it passes line Lb-3 and reaches hot air generator 16 again. On the other hand, air supplied from blower 20 into heat exchanger 18 via line Lc-l and heated there passes line Lb-4 and reaches fluid dryer 4.
The product, which has completely been calcined in fluid calcining furnace 6, passes line La-5 and is sent to high speed cooling device 8 by screw feeder 7. High speed cooling device 8 is a fluidized bed type of cooler equipped with a porous plate.
Cold air supplied by cooling fan 21 via line Lb~7 fluidizes the calcined product and rapidly cools it. Hot air leaving the high speed cooling device 8 passes line Lb-8 and reaches second fluid dryer 13 mentioned later where it is used as a drying medium for fluid dryer 13. The residence time of calcined product in the high speed cooling device 8 is about 10 minutes.
llZS'534 Product cooled in hiyh speed cooling device 8 passes line La-6 and reaches pulverizer 9 where it is pulverized into powder, after which it is transportecl to product storage tank 10 via line La-7. Floating dust leaving product storage tank 10 passes line Lc~3 and is recovered, after which it is returned to pulverizer 9 via Lc-4 by transporting fan 22. The product in storage tank 10 is shipped as a powdery product A-l via screw feeder 11 and line La-8. Otherwise, the product is sent to granu-lator 12 where it is kneaded together with a binder, i.e., water or other water-soluble binder fed from binder tank 23 via line Lf and granulated, after which is passes line La-9, is dried in second fluid dryer 13, passes line La-10 and is then shipped as a granular product A-2. Floating dust leaving second fluid dryer 13 passes line Lc-5, is recovered in dry dust chamber 24, then passes line Ld-2 and is finally recovered in line La-7.
Waste gas leaving dry dust chamber 17 is driven by waste gas gan 25 and passes lines Lc-6 and Lc-8 to be released into the atmosphere from chimney 27, while waste gas leaving dry dust chamber 24 is driven by waste gas fan 26 and passes lines Lc-7 and Lc-9 to be released into the atmosphere via chimney 27.
A concrete example of the above-mentioned process is described below.
Starting materials were measured in continuous quanti-tative feeders la-lf in the following proportions:
0.88 T/H of 45% caustic potash solution as a binder, 0.436 T/H of potassium carbonate, 0.136 T/H of magnesium hydroxide, 0.4 T/H of pulverized coal, and 2.148 T/H of fly ash.
The materials were sent to continuous kneader 2 and kneaded therein. After kneading, the slimy starting mixture was supplied to extruder 3 where it was granulated into cylindrical granules having a diameter of 3 mm and a length of 5 mm.
Then, the granules were sent to fluid dryer 4 where they were dried at 250C for 10 minutes until they reached absolute dryness. Subsequently, the granules were sent to fluid calcining furnace 6 where they were calcined at 1,000C
for 15 minutes. After calcination, the product was sent to high speed cooler 8 where it was cooled with cold air for 15 minutes.
Claims (31)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS;
1, A process for producing citric acid soluble potassium silicate fertilizer, said process comprising: (a) forming a mixture comprising a 40 to 50% solution of caustic potash as a binder in an amount of 20 to 25 parts by weight based on the mix-ture, potassium carbonate in an amount of 9 to 12 parts by weight based on the mixture, fly ash in an amount of 50 to 70 parts by weight based on the mixture and pulverized coal in an amount of 5 to 30 parts by weight based on the mixture; (b) kneading said mixture by means of a continuous kneader; (c) forming the result-ing kneaded mixture into granules by means of an extruder; (d) drying said granules to a state of substantially absolute dryness by means of a fluidized dryer; and (e) calcining the resulting dried granules, at a temperature of from 900°C to 1100°C, by means of a fluidized calcining furnace in order to chemically react the potassium with silicon present in said fly ash and thereby form a citric acid soluble potassium silicate.
2. A process according to claim 1, wherein the product resulting from said fluidized calcining furnace is cooled by means of a high speed cooling device, then pulverized into powder by means of a pulverizer, transported into a product storage tank and stored therein.
3. A process according to claim 2, wherein the powder is carried out of said product storage tank by means of a screw feeder and shipped as a powdery product.
4. A process according to claim 2, wherein the powder is moistened and then granulated by means of a screw feeder, and the product thus granulated is dried by means of a second fluidized dryer and shipped as a granular product.
5. A process according to claim 4, wherein said powder is moistened with water or a water-soluble binder.
6. A process according to claim 1, wherein waste gas containing floating dust leaves said fluidized dryer, and said dust is captured by means of a dry dust chamber and returned to said continuous kneader.
7. A process according to claim 1, wherein waste gas leaves said fluidized dryer, and a part of said waste gas is accelerated by means of a recycling fan and returned to the fluidized dryer.
8. A process according to claim 1, wherein high temperature waste gas leaves said fluidized calcining furnace, and said gas is introduced to a heat exchanger to transmit waste heat to low temperature air from a secondary source, and the air thus heated is supplied to said fluidized dryer and used as a drying medium.
9. A process according to claim 1, wherein high tem-perature waste gas leaves said fluidized calcining furnace, and said gas is introduced to a heat exchanger to transmit waste heat to low temperature air from a secondary source, and said gas thereafter is returned to a generator for providing hot air to said calcining furnace.
10. A process according to claim 2, wherein high tem-perature waste gas leaves said high speed cooling device, and said waste gas is supplied to said fluidized dryer and used as a drying medium.
11. A process according to claim 2, wherein high tem-perature waste gas leaves said high speed cooling device, and said waste gas is introduced to a second fluidized dryer and used as a drying medium.
12. A process according to claim 4, wherein high tem-perature waste gas leaves said high speed cooling device, and said waste gas is introduced to a second fluidized dryer and used as a drying medium.
13. A process according to claim 1, wherein high tem-perature waste gas leaves said fluidized calcining furnace, and said waste gas is led to a heat exchanger to transmit waste heat to low temperature air from a secondary source, the air thus heated is led to a primary line of a second heat exchanger to transmit its heat to air from a secondary line, and the air thus heated is led to a second fluidized dryer and used as a drying medium.
14. A process according to claim 4, wherein high tem-perature waste gas leaves said fluidized calcining furnace, and said waste gas is led to a heat exchanger to transmit waste heat to low temperature air from a secondary source, the air thus heated is led to a primary line of a second heat exchanger to transmit its heat to air from a secondary line, and the air thus heated is led to a second fluidized dryer and used as a drying medium.
15. A process according to claim 11, wherein waste gas containing floating dust leaves the second fluidized dryer, and said dust is captured by means of a dry dust chamber and re-turned to a product storage tank.
16. A process according to claim 1, wherein a high temperature gas obtained by burning a liquefied gas or a fuel oil in a hot air generator is supplied to said fluid calcining furnace and used as a calcining medium.
17. A process according to claim 1, wherein drying in said fluidized dryer is carried out at a temperature of about 200°C to about 300°C for about 10 minutes.
18. A process according to claim 1, wherein calcination in said fluidized calcining furnace is carried out at a tempera-ture of about 600°C to about 1,100°C for about 15 minutes.
19. A process according to claim 1, wherein said granules have a size of about 3 mm to about 5 mm.
20. An apparatus for producing a citric acid soluble potassium silicate fertilizer according to the process of claim 1, which apparatus comprises:
(a) a plurality of continuous quantitative feeders for supplying said binder, said potassium source, said fly ash and said pulverized coal for forming said mixture;
(b) a continuous kneader for continuously kneading said mixture;
(c) an extruder for forming the resulting kneaded mixture into granules;
(d) a fluidized dryer for drying the granules to a state of substantially absolute dryness;
(e) a fluidized calcining furnace for calcining dried granules in order to chemically react potassium with silicon present in the fly ash and thereby form a citric acid soluble potassium silicate; and (f) a cooling device for cooling the resulting calcined product.
(a) a plurality of continuous quantitative feeders for supplying said binder, said potassium source, said fly ash and said pulverized coal for forming said mixture;
(b) a continuous kneader for continuously kneading said mixture;
(c) an extruder for forming the resulting kneaded mixture into granules;
(d) a fluidized dryer for drying the granules to a state of substantially absolute dryness;
(e) a fluidized calcining furnace for calcining dried granules in order to chemically react potassium with silicon present in the fly ash and thereby form a citric acid soluble potassium silicate; and (f) a cooling device for cooling the resulting calcined product.
21. Apparatus according to claim 20, additionally equipped with: a pulverizer for pulverizing calcined and cooled product; a product storage tank for storing product pulverized in said pulverizer; a screw feeder for transporting product to said product storage tank; and means for removing pulverized product from said storage tank and transporting it to packaging means.
22. Apparatus according to claim 20, additionally equipped with: a pulverizer for pulverizing calcined and cooled product; a product storage tank for storing product pulverized in said pulverizer; a screw feeder for transporting product to said product storage tank; means for adding a binder to pulverized product; a granulator for granulating the resulting binder-contain-ing mixture into granules; a second fluidized dryer for drying the granules formed by said granulator; and means for removing the granular product from said second fluidized dryer and trans-porting it to packaging means.
23. Apparatus according to claim 21, wherein said fluidized dryer is equipped with a dry dust chamber for recover-ing floating dust in waste gas from said dryer, said dry dust chamber being connected to said fluidized dryer via piping.
24. Apparatus according to claim 21, wherein said fluidized calcining furnace is equipped with a hot air generator for generating a calcining medium, said hot air generator being connected to said fluidized calcining furnace via piping.
25. Apparatus according to claim 21, wherein said fluidized calcining furnace is equipped with a heat exchanger for recovering waste heat from waste gas from said furnace, said heat exchanger being connected with said fluidized calcining furnace via piping, and waste heat recovered is utilized in the fluidized dryer.
26. Apparatus according to claim 21, wherein said fluidized calcining furnace is equipped with a first heat exchang-er and a second heat exchanger for recovering waste heat, both the heat exchangers being connected to said calcining furnace via piping, and waste heat recovered is utilized in a second fluidized dryer.
27. Apparatus according to claim 22, wherein said second fluidized dryer is equipped with a recovering device for floating dust present in waste gas therefrom, said recovering device being connected to said second dryer via piping.
28. Apparatus according to claim 26, wherein said second heat exchanger is equipped with a recovering device for floating dust present in waste gas after being heat exchanged, said recovering device being connected to said second fluidized dryer via piping.
29. Apparatus according to claim 21, wherein said plurality of quantitative feeders include at least one reserve feeder.
30. Apparatus according to claim 20, wherein said feeders continuously measure and feed said potassium source, said fly ash and said pulverized coal and feed these substances at predetermined rates.
31. A process according to claim 1, 2 or 3, in which the mixture contains 3 to 4 parts by weight of magnesium hydroxide.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP12366878A JPS5551784A (en) | 1978-10-09 | 1978-10-09 | Method and apparatus for manufacturing potassium silicate fertilizer |
| JP123668/1978 | 1978-10-09 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1125534A true CA1125534A (en) | 1982-06-15 |
Family
ID=14866331
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA337,070A Expired CA1125534A (en) | 1978-10-09 | 1979-10-05 | Process for producing potassium silicate fertilizer and apparatus for practicing said process |
Country Status (7)
| Country | Link |
|---|---|
| JP (1) | JPS5551784A (en) |
| AU (1) | AU529781B2 (en) |
| CA (1) | CA1125534A (en) |
| DE (1) | DE2939978C2 (en) |
| FR (1) | FR2438637A1 (en) |
| GB (1) | GB2032903B (en) |
| ZA (1) | ZA795023B (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CH645083A5 (en) * | 1980-05-20 | 1984-09-14 | Escher Wyss Ag | METHOD AND DEVICE FOR RECALCINATING A SLAVE CONTAINING CALCIUM CARBONATE. |
| IL276686B1 (en) | 2018-02-27 | 2024-04-01 | Dead Sea Works Ltd | Potash dust granulation process |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE1252212B (en) * | ||||
| JPS5122570A (en) * | 1974-08-14 | 1976-02-23 | Ube Industries | Kankoseikarihiryono seizohoho |
-
1978
- 1978-10-09 JP JP12366878A patent/JPS5551784A/en active Pending
-
1979
- 1979-09-21 ZA ZA00795023A patent/ZA795023B/en unknown
- 1979-10-02 DE DE2939978A patent/DE2939978C2/en not_active Expired
- 1979-10-03 GB GB7934229A patent/GB2032903B/en not_active Expired
- 1979-10-05 FR FR7924921A patent/FR2438637A1/en active Granted
- 1979-10-05 CA CA337,070A patent/CA1125534A/en not_active Expired
- 1979-10-09 AU AU51594/79A patent/AU529781B2/en not_active Ceased
Also Published As
| Publication number | Publication date |
|---|---|
| FR2438637A1 (en) | 1980-05-09 |
| AU529781B2 (en) | 1983-06-23 |
| GB2032903A (en) | 1980-05-14 |
| GB2032903B (en) | 1983-05-11 |
| DE2939978C2 (en) | 1983-12-22 |
| JPS5551784A (en) | 1980-04-15 |
| DE2939978A1 (en) | 1980-04-24 |
| FR2438637B1 (en) | 1982-06-25 |
| ZA795023B (en) | 1980-09-24 |
| AU5159479A (en) | 1980-04-17 |
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