CA1130969A - Method for pressing salts on roll presses - Google Patents
Method for pressing salts on roll pressesInfo
- Publication number
- CA1130969A CA1130969A CA328,478A CA328478A CA1130969A CA 1130969 A CA1130969 A CA 1130969A CA 328478 A CA328478 A CA 328478A CA 1130969 A CA1130969 A CA 1130969A
- Authority
- CA
- Canada
- Prior art keywords
- rolls
- roll
- pressing
- salts
- press
- 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
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B30—PRESSES
- B30B—PRESSES IN GENERAL
- B30B11/00—Presses specially adapted for forming shaped articles from material in particulate or plastic state, e.g. briquetting presses, tabletting presses
- B30B11/18—Presses specially adapted for forming shaped articles from material in particulate or plastic state, e.g. briquetting presses, tabletting presses using profiled rollers
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J2/00—Processes or devices for granulating materials, e.g. fertilisers in general; Rendering particulate materials free flowing in general, e.g. making them hydrophobic
- B01J2/22—Processes or devices for granulating materials, e.g. fertilisers in general; Rendering particulate materials free flowing in general, e.g. making them hydrophobic by pressing in moulds or between rollers
-
- 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
- C05D1/02—Manufacture from potassium chloride or sulfate or double or mixed salts thereof
Landscapes
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Organic Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Fertilizers (AREA)
- Glanulating (AREA)
- Press-Shaping Or Shaping Using Conveyers (AREA)
Abstract
ABSTRACT OF THE INVENTION
A method of pressing salts on roll presses having rolls which are driven in unison and have profiled surfaces such as ridged or honeycombed surfaces, the salt being fed into the nip or gap between the rolls. The method includes a. feeding the material to the press at a temperature above 120°C, b. pressing carried out with a specific press force at least equal to 4.5 t/cm, c. the circumferential velocity of the rolls being between 0.55 and 0.75 m/sec, d. the surface of the rolls being maintained at a temperature below 80°C.
A method of pressing salts on roll presses having rolls which are driven in unison and have profiled surfaces such as ridged or honeycombed surfaces, the salt being fed into the nip or gap between the rolls. The method includes a. feeding the material to the press at a temperature above 120°C, b. pressing carried out with a specific press force at least equal to 4.5 t/cm, c. the circumferential velocity of the rolls being between 0.55 and 0.75 m/sec, d. the surface of the rolls being maintained at a temperature below 80°C.
Description
6~'3 The inve~tion rela-tes to a method for pressing salts in roll presses having rolls driven in unison, the roll surface being profiled, in particular ridged or honeycombed, where the sal-t is fed into the nip or gap between the rolls by means of, for example, screw conveyors.
Certain salts used as fertilisers, in particular po-tassium salts, are produced during manufacture as material of relatively small particle size wh.ich is unsuitable, in this form, for mechanical spreading. These salts for use as fertilisers are therefore usually pressed in roll presses so as to produce a granulate with particle size of, for example, between 1 and 4 mm.
Rock salt is also pressed and granulated in a similar manner when of small particIe size.
When the salts are presse~ by means of rolls having profiled surfaces a good pick-up of the salt and th~ls a food filling of the roll surface i.s achieved. Rolls of this type, like the more generally used smooth-surface rolls, have hitherto been driven in such a way as to produce shells which do not ex-ceed thickness of approximately 8 to 10 mm. Hitherto attempts to increase the throughput have been implemented by increasing the circumferential velocity of the rolls. However, limits to the increase in circumferential velocity arise from the fact that the above cer-tain circumferential velocities it is no longer possible to achieve satisfactory pressing of the shell.
A criterion for the quality of granulates of salts used as fertiliser is the so-called abrasive resistance. This is defined as the amount of salt which i5 abraded from the gra-nulate during shaking of the granulate with steel spheres within a predetermined time. The lower the amount of salt abraded the better is the quality.
Certain salts used as fertilisers, in particular po-tassium salts, are produced during manufacture as material of relatively small particle size wh.ich is unsuitable, in this form, for mechanical spreading. These salts for use as fertilisers are therefore usually pressed in roll presses so as to produce a granulate with particle size of, for example, between 1 and 4 mm.
Rock salt is also pressed and granulated in a similar manner when of small particIe size.
When the salts are presse~ by means of rolls having profiled surfaces a good pick-up of the salt and th~ls a food filling of the roll surface i.s achieved. Rolls of this type, like the more generally used smooth-surface rolls, have hitherto been driven in such a way as to produce shells which do not ex-ceed thickness of approximately 8 to 10 mm. Hitherto attempts to increase the throughput have been implemented by increasing the circumferential velocity of the rolls. However, limits to the increase in circumferential velocity arise from the fact that the above cer-tain circumferential velocities it is no longer possible to achieve satisfactory pressing of the shell.
A criterion for the quality of granulates of salts used as fertiliser is the so-called abrasive resistance. This is defined as the amount of salt which i5 abraded from the gra-nulate during shaking of the granulate with steel spheres within a predetermined time. The lower the amount of salt abraded the better is the quality.
- 2 -~13~9 It is an object of the invention to devise a method by means of which it is possible to produce, with high through-put/ shells of particularly high strength from which a granulate with high abrasive resistance can be manufactured.
According to the invention there is provided a method for pressing salts in a roll press having rolls driven in unison where the surfaces of the rolls are profiled and the salt is fed into the nip or gap between the rolls, the method including a. feeding the material to the press at a temperature above 12ooc~
b. pressing the material with a specific press force equal to or greater than 4.5 t/cm width of the roll, c. driving said rolls at a circumferential velocity be-tween 0.55 and 0.75 m/sec, and d. maintaining the surface of the rolls at a tempera-ture below 80C.
By means of the method according to the invention a granulate is produced which has an abrasive resistance which is considerably greater than the abrasive resistance of salts press-ed by known methods. The abrasive resistance is improved by amagnitude of 30-50~.
~ urprisingly, it was found that, in spite of the rela-tively low circumferential velocity, a high throughput can be achieved and, in particular, it is possible in the method accord-ing to the invention to increase the thickness of the shell con-sidera~ly. Shell thicknesses greater than 14 mm can be achieved by the method according to the invention. Shell thicknesses of 16 mm have been achieved with a similar abrasive resistance of the granulate. When the thickness of the shell is increased it is necessary to adjust the specific press force. For example, ~ - 3 -~:309G~
the shell thickness of 16 mm was achieved for potassium salts by means of a speciflc press force of about 5.5 t/cm. A con-siderable improvement in the circulation ratio of feed material to shell is also achieved in the method according to the inven--tion. For example, a ratio of shell to feed material greater than 90% was achieved, that is at least 90% of the feed of sma~ll particle size was pressed to form ,; ~
. .
- 3a -~`;
' ~ ,.i ` ~3~6g a shell capable of being worked further.
The shell was then broken by using an impact pulveriser. The granulate was then separated into three fraction3 by sieving.
The granulatewith a predetermined particle size, For example 1-4 mm, was removed as granules of usable size. Granulate with a particle size less than 1 mm. - undersiz0 - was returned to the fine feed material for the press and pressed againO Granulate with particle size greater than 4 mm was milled again.
A ratio of undersize to usable granules of about 1:1 i5 achieved 1~ in the method according to the invention. The circulation arnount is thus reduced to about half the total flow of material. In ~nown smooth roll presses the material circulated is yreater than 30~0 of the usable granules produced.
Thus a decrease in the specific electric power consumption is qchieve~J by comparison with smooth roll presse3. Calculated on the total plant, it is possible to count on a halving of the specific electrical power consumption, that is the amount of electrical power consumed for unit weight of usable material.
Owing to the relatively low circumferential velocity together with the profiling of the roll surfaces a particularly favourable de-aeration of the material is also achieved so that it is possible to produce a shell substantially free from interruptions.
Because of the temperature of the roll surFaces~ wllich is below BûC, in particular within the range 40C to 70C, melting of the salt on the surface of the roll is avoided. The shell has a hard polished surface. The surface temperature which it is possible to achieve on the roll depends essentially on the temperature of the cooling water available and on the temperature of the surroundings. Attempts should be made to secure as low a temperature as possible, preferably within the range from 40 to 60C.
r.
5_ The following are used for the method:
1. A roll press with press rolls arranged horizontally against ; one another.
1.1 Roll diameter 1000 mm.
1.2 Working breadth of the rolls 'L250 mm.
; 1.3 Surface honeycombed with cushion-type depressions wlth 1.3.1 maximum depth 5 mm.
1.3.2 lateral displacement of the honeycomb by 50~0 in successive rows.
1.3.3 displacement of the honeycombed depressions ~y 50 in the circumferential direction on the rolls applied against each other.
1.4 Cooling of the rolls by means of cooling medium chan~els arranged below the surface of the rolls 1.5 Drive 1.5.1 installed operating,power 630 KW
1.5.2 r.p.rn. of the rolls 12 r.p.m., corresponding to a circumferential velocity of 0.6 m/sec 1.5.3 synchronised drive of th~ roll pair.
1.6 Feed by rneans of filling screws, 5-fold.
2. Feed material loose potassium salts 2.1 Particle si~e 60 (60 potassium salt) 2.2 salt temperature 140C.
According to the invention there is provided a method for pressing salts in a roll press having rolls driven in unison where the surfaces of the rolls are profiled and the salt is fed into the nip or gap between the rolls, the method including a. feeding the material to the press at a temperature above 12ooc~
b. pressing the material with a specific press force equal to or greater than 4.5 t/cm width of the roll, c. driving said rolls at a circumferential velocity be-tween 0.55 and 0.75 m/sec, and d. maintaining the surface of the rolls at a tempera-ture below 80C.
By means of the method according to the invention a granulate is produced which has an abrasive resistance which is considerably greater than the abrasive resistance of salts press-ed by known methods. The abrasive resistance is improved by amagnitude of 30-50~.
~ urprisingly, it was found that, in spite of the rela-tively low circumferential velocity, a high throughput can be achieved and, in particular, it is possible in the method accord-ing to the invention to increase the thickness of the shell con-sidera~ly. Shell thicknesses greater than 14 mm can be achieved by the method according to the invention. Shell thicknesses of 16 mm have been achieved with a similar abrasive resistance of the granulate. When the thickness of the shell is increased it is necessary to adjust the specific press force. For example, ~ - 3 -~:309G~
the shell thickness of 16 mm was achieved for potassium salts by means of a speciflc press force of about 5.5 t/cm. A con-siderable improvement in the circulation ratio of feed material to shell is also achieved in the method according to the inven--tion. For example, a ratio of shell to feed material greater than 90% was achieved, that is at least 90% of the feed of sma~ll particle size was pressed to form ,; ~
. .
- 3a -~`;
' ~ ,.i ` ~3~6g a shell capable of being worked further.
The shell was then broken by using an impact pulveriser. The granulate was then separated into three fraction3 by sieving.
The granulatewith a predetermined particle size, For example 1-4 mm, was removed as granules of usable size. Granulate with a particle size less than 1 mm. - undersiz0 - was returned to the fine feed material for the press and pressed againO Granulate with particle size greater than 4 mm was milled again.
A ratio of undersize to usable granules of about 1:1 i5 achieved 1~ in the method according to the invention. The circulation arnount is thus reduced to about half the total flow of material. In ~nown smooth roll presses the material circulated is yreater than 30~0 of the usable granules produced.
Thus a decrease in the specific electric power consumption is qchieve~J by comparison with smooth roll presse3. Calculated on the total plant, it is possible to count on a halving of the specific electrical power consumption, that is the amount of electrical power consumed for unit weight of usable material.
Owing to the relatively low circumferential velocity together with the profiling of the roll surfaces a particularly favourable de-aeration of the material is also achieved so that it is possible to produce a shell substantially free from interruptions.
Because of the temperature of the roll surFaces~ wllich is below BûC, in particular within the range 40C to 70C, melting of the salt on the surface of the roll is avoided. The shell has a hard polished surface. The surface temperature which it is possible to achieve on the roll depends essentially on the temperature of the cooling water available and on the temperature of the surroundings. Attempts should be made to secure as low a temperature as possible, preferably within the range from 40 to 60C.
r.
5_ The following are used for the method:
1. A roll press with press rolls arranged horizontally against ; one another.
1.1 Roll diameter 1000 mm.
1.2 Working breadth of the rolls 'L250 mm.
; 1.3 Surface honeycombed with cushion-type depressions wlth 1.3.1 maximum depth 5 mm.
1.3.2 lateral displacement of the honeycomb by 50~0 in successive rows.
1.3.3 displacement of the honeycombed depressions ~y 50 in the circumferential direction on the rolls applied against each other.
1.4 Cooling of the rolls by means of cooling medium chan~els arranged below the surface of the rolls 1.5 Drive 1.5.1 installed operating,power 630 KW
1.5.2 r.p.rn. of the rolls 12 r.p.m., corresponding to a circumferential velocity of 0.6 m/sec 1.5.3 synchronised drive of th~ roll pair.
1.6 Feed by rneans of filling screws, 5-fold.
2. Feed material loose potassium salts 2.1 Particle si~e 60 (60 potassium salt) 2.2 salt temperature 140C.
3. ûperation 3.1 mean thickness of shell 14 mm.
3.2 specific press force 4.5 t/cm 3.2 throughput ~ 3.3.1 gross 80 t/h ; 3.3.2 shell production 75 t/h 3.3.3 yield of granulate particle size 1-4 mm 45 t/h 3.3.4 Abrasive resistance high.
3,4 Power consunnption of the press 425 KW.
3.2 specific press force 4.5 t/cm 3.2 throughput ~ 3.3.1 gross 80 t/h ; 3.3.2 shell production 75 t/h 3.3.3 yield of granulate particle size 1-4 mm 45 t/h 3.3.4 Abrasive resistance high.
3,4 Power consunnption of the press 425 KW.
4. When the mean thickness of the shell is increased to 16 mrn, with a proportional increase in power consumption, a proportional increase in the throughput data of less than 3.3 is achieved with -r 3L~L3~6 the ~ame granule quality.
~y way of further axample, the method according to the~invention is illustrated in the accompanying flow diagram. The ~alt, for ex~mple a loose potassium salt with a particle size less S than 0.2 to 0.3 mm., is~ as shown by the arrow 2, led to a bunker 4 from which it is fed ~hroughl a conduit 6 to a roll press 8 provided with two rolls rotating in opposite directions about parallel horizontal axes. The material is fed into the nip or gap between the rolls by means of screw conveyors, and in particular by means of a multip~icity of screw conveyors arranged side by side in the axial direction of the rolls.
The rolls are profiled on their surfaces, in particular ridged or honeycombed. The rolls are cooled and for this purpose tlle roll pres~ provided with ~n :Inlet 10 and an outlet 12 for cooling water.
The shell pressed in the roll press ~ i3 conveyed to an irnp~ct pulveriser 16 by means of a conveyor device 14. The pulvsrised matarial at lB is conveyed to a threefold sieve 20~where material of large particle sizeJ greater than 4 mm. is first removed by sieving. This material is returned to ths material fIow before the impact pulveriser :L6 and is again pulverised.
The material with particle size from 1 to 4 mm. is the usable material.
The fines, with particle size less than 1 mm. which are sieYed off are returned to the feed bunker 4 by means of the conveyor davice 22.
The material pressed in the roll press contains a certain ~nount of unpressed fines. Material wi-th a particle si~e le~s than 1 mm. is sieved off in a sieving device 24 and is returnedJ together with khe fines sieved off in the sieving device 20, to the feed bunker 4 by means of the conveyor device 22.
~y way of further axample, the method according to the~invention is illustrated in the accompanying flow diagram. The ~alt, for ex~mple a loose potassium salt with a particle size less S than 0.2 to 0.3 mm., is~ as shown by the arrow 2, led to a bunker 4 from which it is fed ~hroughl a conduit 6 to a roll press 8 provided with two rolls rotating in opposite directions about parallel horizontal axes. The material is fed into the nip or gap between the rolls by means of screw conveyors, and in particular by means of a multip~icity of screw conveyors arranged side by side in the axial direction of the rolls.
The rolls are profiled on their surfaces, in particular ridged or honeycombed. The rolls are cooled and for this purpose tlle roll pres~ provided with ~n :Inlet 10 and an outlet 12 for cooling water.
The shell pressed in the roll press ~ i3 conveyed to an irnp~ct pulveriser 16 by means of a conveyor device 14. The pulvsrised matarial at lB is conveyed to a threefold sieve 20~where material of large particle sizeJ greater than 4 mm. is first removed by sieving. This material is returned to ths material fIow before the impact pulveriser :L6 and is again pulverised.
The material with particle size from 1 to 4 mm. is the usable material.
The fines, with particle size less than 1 mm. which are sieYed off are returned to the feed bunker 4 by means of the conveyor davice 22.
The material pressed in the roll press contains a certain ~nount of unpressed fines. Material wi-th a particle si~e le~s than 1 mm. is sieved off in a sieving device 24 and is returnedJ together with khe fines sieved off in the sieving device 20, to the feed bunker 4 by means of the conveyor device 22.
Claims (8)
1. A method for pressing salts in a roll press having rolls driven in unison where the surfaces of the rolls are pro-filed and the salt is fed into the nip or gap between the rolls, the method including a. feeding the material to the press at a temperature above 120°C, b. pressing the material with a specific press force equal to or greater than 4.5 t/cm width of the roll, c. driving said rolls at a circumferential velocity between 0.55 and 0.75 m/5ec, and d. maintaining the surface of the rolls at a tempera-ture below 80°C.
2. The method of claim 1 wherein said salt is fed in-to said gap by means of screw conveyors.
3. The method according to claim 1 in which the rolls have a circumferential velocity of between 0.6 and 0.7 m/sec.
4. The method according to claim 1, 2, or 3 in which the material to be pressed is fed at a temperature between 130°C
and 140°C.
and 140°C.
5. The method according to claim 1, in which the sur-face of the rolls is maintained at a temperature between 40°C and 70°C.
6. The method according to claim 5 in which the sur-face of the rolls is maintained at a temperature between 40°C
and 60°C.
and 60°C.
7. The method according to claim 1, 2, or 3 in which the surfaces of the rolls are ribbed.
8. The method according to claim 1, 2, or 3 in which the surfaces of the rolls are formed with honeycomb-like depres-sion.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19782824827 DE2824827B2 (en) | 1978-06-06 | 1978-06-06 | Process for pressing salts on roller presses |
| DEP2824827.3-41 | 1978-06-06 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1130969A true CA1130969A (en) | 1982-09-07 |
Family
ID=6041186
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA328,478A Expired CA1130969A (en) | 1978-06-06 | 1979-05-28 | Method for pressing salts on roll presses |
Country Status (4)
| Country | Link |
|---|---|
| JP (1) | JPS5518292A (en) |
| CA (1) | CA1130969A (en) |
| DD (1) | DD144151A5 (en) |
| DE (1) | DE2824827B2 (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5924128U (en) * | 1982-08-04 | 1984-02-15 | 新東工業株式会社 | briquetting machine |
| DE3802173C1 (en) * | 1988-01-26 | 1988-09-08 | Maschinenfabrik Koeppern Gmbh & Co Kg, 4320 Hattingen, De | |
| DE102008020137A1 (en) * | 2008-04-22 | 2009-10-29 | Franz Mayer und Paul Mayer GbR (vertretungsberechtigter Gesellschafter: Herrn Paul Mayer, 83313 Siegsdorf) | Food product in the form of a crystalline food e.g. salt, comprises form-stable compact plates or tablets, where the flowable crystalline food present in grain or granulate form is directly injected to the plates or tablets by rolling mill |
| DE102020131638B4 (en) | 2020-11-30 | 2024-03-28 | Maschinenfabrik Köppern Gmbh & Co. Kg | Process for crushing fertilizer slurries in a two-roll mill |
| DE102023106787B3 (en) | 2023-03-17 | 2024-05-08 | Maschinenfabrik Köppern Gmbh & Co. Kg | Plant and process for the production of fertilizer granules |
-
1978
- 1978-06-06 DE DE19782824827 patent/DE2824827B2/en not_active Withdrawn
-
1979
- 1979-05-28 CA CA328,478A patent/CA1130969A/en not_active Expired
- 1979-06-01 JP JP6754579A patent/JPS5518292A/en active Pending
- 1979-06-05 DD DD21340079A patent/DD144151A5/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| DE2824827A1 (en) | 1979-12-13 |
| JPS5518292A (en) | 1980-02-08 |
| DD144151A5 (en) | 1980-10-01 |
| DE2824827B2 (en) | 1980-09-11 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |