CA1216164A - Process for forming prills from sulphur and bentonite - Google Patents
Process for forming prills from sulphur and bentoniteInfo
- Publication number
- CA1216164A CA1216164A CA000458389A CA458389A CA1216164A CA 1216164 A CA1216164 A CA 1216164A CA 000458389 A CA000458389 A CA 000458389A CA 458389 A CA458389 A CA 458389A CA 1216164 A CA1216164 A CA 1216164A
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- bentonite
- weight
- process according
- sulphur
- water
- Prior art date
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Abstract
ABSTRACT OF THE DISCLOSURE
A process for prilling a mixture of sulphur and bentonite to produce a water-degradable prill includes adding dry bentonite in powdered form to molten sulphur at a temperature to provide a molten sulphur-bentonite mixture, forming droplets of the mixture, providing a quenching solution of either sodium chloride, sodium sulphate, potassium chloride or potassium sulphate at a temperature low enough to solidify the sulphur-bentonite mixture, feeding the droplets into the quenching solu-tion, passing the droplets through the quenching solution for a time and at a temperature of the quenching solution sufficient to anneal the droplets into prills, and remov-ing the annealed prills from the quenching solution and drying the prills to a specified temperature and moisture content. This invention relates to new and useful im-provements in the process and resultant product of form-ing prills from sulphur for fertilizing purposes, and to reducing the dust normally present with prills made en-tirely from sulphur.
A process for prilling a mixture of sulphur and bentonite to produce a water-degradable prill includes adding dry bentonite in powdered form to molten sulphur at a temperature to provide a molten sulphur-bentonite mixture, forming droplets of the mixture, providing a quenching solution of either sodium chloride, sodium sulphate, potassium chloride or potassium sulphate at a temperature low enough to solidify the sulphur-bentonite mixture, feeding the droplets into the quenching solu-tion, passing the droplets through the quenching solution for a time and at a temperature of the quenching solution sufficient to anneal the droplets into prills, and remov-ing the annealed prills from the quenching solution and drying the prills to a specified temperature and moisture content. This invention relates to new and useful im-provements in the process and resultant product of form-ing prills from sulphur for fertilizing purposes, and to reducing the dust normally present with prills made en-tirely from sulphur.
Description
PROCESS FOR FORMING PILL FROM SELFWARE AND BENTONITE
BACKGROUND
In order for Selfware to be used as a soil add-live it is essential that the Selfware be in a finely divided form and it is known to provide such pills by mixing Selfware with certain mineral clays such as bent-note.
It is well known to mix bentonite with molten Selfware and to pour the mixture into sheet form and, when it has cooled, community same, and separate to a pro-determined particle size, but unfortunately excessive dust is produced both in the formation of the product and in the end product itself.
It is also known to produce a mixture of molten Selfware and bentonite in a pellet or pill form, and in order to prevent the undesirable premature swelling of the bentonite, to quench same in a liquid fertilizer rather than quenching the pills in water. An example of this is United States Patent ~133669. Unfortunately, utilizing a liquid fertilizer coolant to form the pills results in an annealing process which is not entirely satisfactory, is difficult to control and does not give I
the desired compressive strength to the pill to prevent breakage during handling.
SUMMARY OF THE INVENTION
The present invention overcomes disadvantages inherent with prior art teachings and in accordance with the invention, there is provided a process to produce pills of a bentonite and Selfware mixture, that are de-tradable in water, and which consists of the steps of adding I to 15% dried bentonite by weight to 99% to 85%
Moulton Selfware by weight with continuous and thorough shear mixing at a temperature between 238F and 318F, forming droplets of the mixture, providing a quenching solution selected from a group consisting of sodium chloride, sodium sulfite, potassium chloride and potash slum sulfite, passing the droplets through the quenching solution for a time sufficient to anneal the droplets into pills, and then removing the annealed pills from the solution and fluidized air drying them at a tempera-lure of between 150F and 212F so that they contain less thin 0.5% water by weight with a preferred content being less than 0.1% water by weight.
It will of course be appreciated that the above limitations are approximate and that there are preferred lZ~6~4 temperatures and the like as both will hereinafter be explained.
This process, particularly using the quenching solution mentioned, inhibits the bentonite from swelling during storage and gives the pills the required compress size strength to maintain their integrity during storage and transportation with the absolute minimum production of dust during the handling thereof.
Another advantage of the invention is to pro-vise a process and product in which the size can be varied depending upon design parameters and in which the final moisture content may be strictly controlled to further inhibit any premature swelling and subsequent degradation of the pills until used.
With the foregoing in view, and other ad van-taxes as will become apparent to those skilled in the art to which this invention relates as this specification proceeds, the invention is herein described by reference to the accompanying drawings forming a part hereof, which includes a description of the best mode known to the applicant and of the preferred typical embodiment of the principles of the present invention, in which:
DESCRIPTION OF THE DRAWING
-Figure 1 is a schematic diagram of the process of forming the pills of the present invention.
In the drawing like characters of reference indicate corresponding parts in the different figures.
DETAILED DESCRIPTION
Proceeding therefore to describe the invention in detail, reference should be made to the drawing which shows the apparatus schematically and includes a mix tank 10 heated by steam coils 11 in order to maintain a mix temperature of between approximately 238F and 318F. The preferred temperature is approximately 265F.
The mixture within tank 10 consists of between 1% and 15% bentonite by weight and between 99% and 85%
of molten swallower.
The bentonite should be in powdered form and of a dry lattice expanding type containing montmorillo-note with the preferred amount of montmorillonite ox-ceding 70% by weight. The moisture content may exceed 3% by weight, but is preferably less than 3% by weight.
The bentonite is added in dust form at iambi-en temperature from hopper 12 with Selfware being added to mix tank 10. It is mixed slowly so that the them-portray of the mixture is not lowered too rapidly and, as mentioned previously, the mixture within the tank should be maintained at a temperature of approx-irately 265 and a continuous shear mixing by means of mixer 14 and shear plate or baffles 15 in order to pro-vent separation of the bentonite. Selfware temperature is important to prevent the Selfware from solidifying and for maintaining the Selfware at the desired viscosity.
Excessive temperatures not only increase the Selfware viscosity, but also causes excessive polymerization and therefore eventual poor degradation.
As mentioned previously, without continuous shear mixing induced by mixer 14 in conjunction with shear plate or baffles 15 within the tank, the bent-note will settle out.
The degradable characteristics of the result-ant sulphur-bentonite pills may be varied by increase in or decreasing the ratio of bentonite that is added to the Selfware and the efficiency of drying. In gene-fat, large amounts of bentonite will cause the Selfware to degrade faster (in the present context, it is to be understood that degrading means to reduce to smaller particles). Furthermore, the low content of water in the final dry pill will improve the prowls kirk-teristics to absorb free water.
I"
\. I Jo The bentonite particle size used is preferably of the size so that between 95% and 98~ will pass through 200 mesh US. Standard screen. However, bentonite par-tide size may vary between what passes through an 80 mesh screen and what passes through a 325 mesh screen with a higher percentage passing through the 325 mesh screen. In fact, it is desirable that between 75% and 98~ of the bentonite pass through the 325 mesh screen.
The swelling capability of the bentonite should be in a range from about 15 to 30 times. Small amounts of gala-lusts, such as sodium carboxymethyl cellulose or soda ash, may be added to the bentonite to increase its swell-in capability with the result being that the catalyst will speed up the degrading time of the sulphur-bentonite mixture when used When thorough mixing has occurred in tank 10 and the desired temperature has been obtained, pump 16 pumps the mixture through feed line 17 to discharge con-trot valve 19.
Reference character 20 illustrates a stainless steel tray with a matrix of holes in the base 21 thereof.
It is this tray which forms the liquid mixture into the streams which eventually form the pills and such a structure is well known and conventional in the art.
The diameter of the holes in the tray may vary between 3/64" and 7/64" depending upon the diameter of pills required as a final product. However it has been found that the preferred opening is a circle having an approximate diameter of 4/64".
The flow control valve 19 is adjusted so that the level of the molten mixture within the tray is be-tweet approximately 1/2" and 2" above the base 21 with the molted sulphur-bentonite mixture being maintained in the range of approximately 238F to approximately 318F.
Steam heating coils or other forms of heating may be provided to pilling tray 20 in order to prevent solid-ligation of the sulphur-bentonite mixture in the pilling tray holes. However heating of the tray is not essential and only would be beneficial during start-up, as the heat from the molten sulphur-bentonite mixture is normally sufficient to prevent the solidification of same within the pilling tray holes.
Pilling tank 22 is provided with a supply of liquid quenching solution 23 and in accordance with the principles of this invention, the liquid quenching soul-lion comprises a chloride or sulfite solution mixture mixed with water in order to maintain a specific gravity of between 1.001 and 1.08. The quenching solution is I
preferably formed by selecting one of the group consist-in of potassium chloride, potassium sulfite, sodium chloride, and sodium sulfite with the preferred quench-in solution being made from potassium chloride. It has been found that such quenching solutions prevent pro-mature swelling of the pills and provide sufficient compressive strength to prevent break-down and powdering prior to application.
Quenching solution 23 is supplied to tank 22 through inlet valve 24 with the level within tank 22 being regulated by whir gate 25. The temperature range of the quenching solution is maintained preferably be-tweet approximately 40F and approximately 100F, being controlled by heat exchanger 26 and steam heating coils 27 or other conventional heating means as will herein-after be described.
To form the sulphur-bentonite pills, the sulphur-bentonite mixture passes through the holes in tray 20 to form a homogeneous stream which falls into quenching solution 23. The quench solution forms a cool-in zone and, as the stream enters the cooling zone, droplets are formed. The droplets are annealed to rota-lively hard smooth pills by the time they reach the bottom of pilling tank 22 at which time they are picked 6~6~
up by means of bucket elevator 28 or the like and the annealed sulphur-bentonite pills along with a small amount of quench solution are discharged out of the top of pilling tank 22 onto chute 29 which directs the pills onto vibrating screen 30 which separates the pills and the quench solution. The quench solution is fed by gravity back into settling tank 32 by means of conduit 38.
The pills then enter a fluidized hot-air dryer Al which includes a source of heat, a heat exchan-germ a method of conveying the pills and a method of circulating air such as a fan. Any suitable combo-newts may be utilized for vibrating screen assembly 13, and the fluidized hot-air dryer 31. As details of these components do not form a part of the invention, it is not believed necessary to describe same further except to say that they are available commercially and are con-ventional for various purposes. However, it should be noted that the fluidized hot-air dryer 31 should fur-nigh hot dry air to be blown over the pills as mystery would not dry them sufficiently and that the them-portray of the drying air should be between approxi-mutely 150F and 212F and retention time shall be such to dry the pills to lower than 0.5% moisture content.
Jo I
Loss of quenching solution 23 through evapo-ration may be made tip by adding more water and more chloride or sulfite crystals to settling tank 32.
The quench solution is circulated from tank 32 along the conduit 33 by pumping means such as pump 34 through filter 35. The purpose of the filter is to remove fine traces of bentonite from the solution which could of-foot the efficiency of the quenching process. Air air-quilting, such as a fan, drives air upward over heat exchanger 26 to effect cooling of the solution to the desired temperature range. If the quenching solution is too cold, then steam heating coils 27, within sell-lying tank 32, may be used to heat the solution to the desired temperature.
The desired size of pills is in the range of 1.0 mm to 5.0 mm in diameter and a combination of factors determine pill size and quality.
size (1) The "head" or pressure forcing the sulphur-bentonite mixture through the holes in pilling tray 20.
BACKGROUND
In order for Selfware to be used as a soil add-live it is essential that the Selfware be in a finely divided form and it is known to provide such pills by mixing Selfware with certain mineral clays such as bent-note.
It is well known to mix bentonite with molten Selfware and to pour the mixture into sheet form and, when it has cooled, community same, and separate to a pro-determined particle size, but unfortunately excessive dust is produced both in the formation of the product and in the end product itself.
It is also known to produce a mixture of molten Selfware and bentonite in a pellet or pill form, and in order to prevent the undesirable premature swelling of the bentonite, to quench same in a liquid fertilizer rather than quenching the pills in water. An example of this is United States Patent ~133669. Unfortunately, utilizing a liquid fertilizer coolant to form the pills results in an annealing process which is not entirely satisfactory, is difficult to control and does not give I
the desired compressive strength to the pill to prevent breakage during handling.
SUMMARY OF THE INVENTION
The present invention overcomes disadvantages inherent with prior art teachings and in accordance with the invention, there is provided a process to produce pills of a bentonite and Selfware mixture, that are de-tradable in water, and which consists of the steps of adding I to 15% dried bentonite by weight to 99% to 85%
Moulton Selfware by weight with continuous and thorough shear mixing at a temperature between 238F and 318F, forming droplets of the mixture, providing a quenching solution selected from a group consisting of sodium chloride, sodium sulfite, potassium chloride and potash slum sulfite, passing the droplets through the quenching solution for a time sufficient to anneal the droplets into pills, and then removing the annealed pills from the solution and fluidized air drying them at a tempera-lure of between 150F and 212F so that they contain less thin 0.5% water by weight with a preferred content being less than 0.1% water by weight.
It will of course be appreciated that the above limitations are approximate and that there are preferred lZ~6~4 temperatures and the like as both will hereinafter be explained.
This process, particularly using the quenching solution mentioned, inhibits the bentonite from swelling during storage and gives the pills the required compress size strength to maintain their integrity during storage and transportation with the absolute minimum production of dust during the handling thereof.
Another advantage of the invention is to pro-vise a process and product in which the size can be varied depending upon design parameters and in which the final moisture content may be strictly controlled to further inhibit any premature swelling and subsequent degradation of the pills until used.
With the foregoing in view, and other ad van-taxes as will become apparent to those skilled in the art to which this invention relates as this specification proceeds, the invention is herein described by reference to the accompanying drawings forming a part hereof, which includes a description of the best mode known to the applicant and of the preferred typical embodiment of the principles of the present invention, in which:
DESCRIPTION OF THE DRAWING
-Figure 1 is a schematic diagram of the process of forming the pills of the present invention.
In the drawing like characters of reference indicate corresponding parts in the different figures.
DETAILED DESCRIPTION
Proceeding therefore to describe the invention in detail, reference should be made to the drawing which shows the apparatus schematically and includes a mix tank 10 heated by steam coils 11 in order to maintain a mix temperature of between approximately 238F and 318F. The preferred temperature is approximately 265F.
The mixture within tank 10 consists of between 1% and 15% bentonite by weight and between 99% and 85%
of molten swallower.
The bentonite should be in powdered form and of a dry lattice expanding type containing montmorillo-note with the preferred amount of montmorillonite ox-ceding 70% by weight. The moisture content may exceed 3% by weight, but is preferably less than 3% by weight.
The bentonite is added in dust form at iambi-en temperature from hopper 12 with Selfware being added to mix tank 10. It is mixed slowly so that the them-portray of the mixture is not lowered too rapidly and, as mentioned previously, the mixture within the tank should be maintained at a temperature of approx-irately 265 and a continuous shear mixing by means of mixer 14 and shear plate or baffles 15 in order to pro-vent separation of the bentonite. Selfware temperature is important to prevent the Selfware from solidifying and for maintaining the Selfware at the desired viscosity.
Excessive temperatures not only increase the Selfware viscosity, but also causes excessive polymerization and therefore eventual poor degradation.
As mentioned previously, without continuous shear mixing induced by mixer 14 in conjunction with shear plate or baffles 15 within the tank, the bent-note will settle out.
The degradable characteristics of the result-ant sulphur-bentonite pills may be varied by increase in or decreasing the ratio of bentonite that is added to the Selfware and the efficiency of drying. In gene-fat, large amounts of bentonite will cause the Selfware to degrade faster (in the present context, it is to be understood that degrading means to reduce to smaller particles). Furthermore, the low content of water in the final dry pill will improve the prowls kirk-teristics to absorb free water.
I"
\. I Jo The bentonite particle size used is preferably of the size so that between 95% and 98~ will pass through 200 mesh US. Standard screen. However, bentonite par-tide size may vary between what passes through an 80 mesh screen and what passes through a 325 mesh screen with a higher percentage passing through the 325 mesh screen. In fact, it is desirable that between 75% and 98~ of the bentonite pass through the 325 mesh screen.
The swelling capability of the bentonite should be in a range from about 15 to 30 times. Small amounts of gala-lusts, such as sodium carboxymethyl cellulose or soda ash, may be added to the bentonite to increase its swell-in capability with the result being that the catalyst will speed up the degrading time of the sulphur-bentonite mixture when used When thorough mixing has occurred in tank 10 and the desired temperature has been obtained, pump 16 pumps the mixture through feed line 17 to discharge con-trot valve 19.
Reference character 20 illustrates a stainless steel tray with a matrix of holes in the base 21 thereof.
It is this tray which forms the liquid mixture into the streams which eventually form the pills and such a structure is well known and conventional in the art.
The diameter of the holes in the tray may vary between 3/64" and 7/64" depending upon the diameter of pills required as a final product. However it has been found that the preferred opening is a circle having an approximate diameter of 4/64".
The flow control valve 19 is adjusted so that the level of the molten mixture within the tray is be-tweet approximately 1/2" and 2" above the base 21 with the molted sulphur-bentonite mixture being maintained in the range of approximately 238F to approximately 318F.
Steam heating coils or other forms of heating may be provided to pilling tray 20 in order to prevent solid-ligation of the sulphur-bentonite mixture in the pilling tray holes. However heating of the tray is not essential and only would be beneficial during start-up, as the heat from the molten sulphur-bentonite mixture is normally sufficient to prevent the solidification of same within the pilling tray holes.
Pilling tank 22 is provided with a supply of liquid quenching solution 23 and in accordance with the principles of this invention, the liquid quenching soul-lion comprises a chloride or sulfite solution mixture mixed with water in order to maintain a specific gravity of between 1.001 and 1.08. The quenching solution is I
preferably formed by selecting one of the group consist-in of potassium chloride, potassium sulfite, sodium chloride, and sodium sulfite with the preferred quench-in solution being made from potassium chloride. It has been found that such quenching solutions prevent pro-mature swelling of the pills and provide sufficient compressive strength to prevent break-down and powdering prior to application.
Quenching solution 23 is supplied to tank 22 through inlet valve 24 with the level within tank 22 being regulated by whir gate 25. The temperature range of the quenching solution is maintained preferably be-tweet approximately 40F and approximately 100F, being controlled by heat exchanger 26 and steam heating coils 27 or other conventional heating means as will herein-after be described.
To form the sulphur-bentonite pills, the sulphur-bentonite mixture passes through the holes in tray 20 to form a homogeneous stream which falls into quenching solution 23. The quench solution forms a cool-in zone and, as the stream enters the cooling zone, droplets are formed. The droplets are annealed to rota-lively hard smooth pills by the time they reach the bottom of pilling tank 22 at which time they are picked 6~6~
up by means of bucket elevator 28 or the like and the annealed sulphur-bentonite pills along with a small amount of quench solution are discharged out of the top of pilling tank 22 onto chute 29 which directs the pills onto vibrating screen 30 which separates the pills and the quench solution. The quench solution is fed by gravity back into settling tank 32 by means of conduit 38.
The pills then enter a fluidized hot-air dryer Al which includes a source of heat, a heat exchan-germ a method of conveying the pills and a method of circulating air such as a fan. Any suitable combo-newts may be utilized for vibrating screen assembly 13, and the fluidized hot-air dryer 31. As details of these components do not form a part of the invention, it is not believed necessary to describe same further except to say that they are available commercially and are con-ventional for various purposes. However, it should be noted that the fluidized hot-air dryer 31 should fur-nigh hot dry air to be blown over the pills as mystery would not dry them sufficiently and that the them-portray of the drying air should be between approxi-mutely 150F and 212F and retention time shall be such to dry the pills to lower than 0.5% moisture content.
Jo I
Loss of quenching solution 23 through evapo-ration may be made tip by adding more water and more chloride or sulfite crystals to settling tank 32.
The quench solution is circulated from tank 32 along the conduit 33 by pumping means such as pump 34 through filter 35. The purpose of the filter is to remove fine traces of bentonite from the solution which could of-foot the efficiency of the quenching process. Air air-quilting, such as a fan, drives air upward over heat exchanger 26 to effect cooling of the solution to the desired temperature range. If the quenching solution is too cold, then steam heating coils 27, within sell-lying tank 32, may be used to heat the solution to the desired temperature.
The desired size of pills is in the range of 1.0 mm to 5.0 mm in diameter and a combination of factors determine pill size and quality.
size (1) The "head" or pressure forcing the sulphur-bentonite mixture through the holes in pilling tray 20.
(2) The hole size in pilling tray 20.
(3) The temperature of the molten Selfware-bentonite mixture.
, t I, ~LZl~
, t I, ~LZl~
(4) The height of the bottom of tray 20 above quenching solution 23.
Quality (1) Sulphur-bentonite composition.
(2) Selfware temperature.
(3) The quenching solution temperature.
(4) The specific gravity thereof.
Quality (1) Sulphur-bentonite composition.
(2) Selfware temperature.
(3) The quenching solution temperature.
(4) The specific gravity thereof.
(5) The amount the solution may have been contaminated by bentonite.
(6) The final moisture content of the pills immediately after the fluidized hot-air dryer 31.
The preferred temperature range has been disk cussed previously. The preferred pressure range is at-twined by adjusting control valve 19 to provide a it-quid "head" in pilling tray 20 from about inch to approximately 2 inches and the preferred hole size is, as mentioned previously, in the range of approximately 3/64 inch to 7/64 inch in diameter.
It is also preferable that the free fall disk lance between base 21 of tray 20 and the surface of quenching solution 23 controlled by whir gate 25, should be maintained at a minimum and the preferred range of free fall distance is approximately 1/2 inch to 2 inches vertical drop.
I I
As mentioned previously, when the pills are removed from quenching solution 23 in tank 22, they are dried before being stored. The pills should be dried to a point where they contain less than 0.5% water by weight. At this point, the pills contain less moist lure than ambient air and therefore are super dry These super dry pills leaving the dryer 31, are screen-Ed into different sizes by conventional sizing screens 36 and are immediately packed in air-tight bags as if-lo lust rated at 37, or stored in humidity controlled bins for transportation and blending with other types of fertilizer.
It would therefore be appreciated that there has been described a process for the manufacture of a water-degradable Selfware product, which product is en-sentially dust free, is extremely durable due to the quenching process increasing the compressive strength thereof, and has good degradation characteristics once exposed to moisture in the soil.
Since various modifications can be made in my invention as hereinafter described, and many apparently widely different embodiments of same made within the spirit and scope of the claims without departing from such spirit and scope, it is intended that all matter contained in the accompanying specification shall be :;
31L;~L6~
interpreted as illustrative only and not in a limiting sense.
The preferred temperature range has been disk cussed previously. The preferred pressure range is at-twined by adjusting control valve 19 to provide a it-quid "head" in pilling tray 20 from about inch to approximately 2 inches and the preferred hole size is, as mentioned previously, in the range of approximately 3/64 inch to 7/64 inch in diameter.
It is also preferable that the free fall disk lance between base 21 of tray 20 and the surface of quenching solution 23 controlled by whir gate 25, should be maintained at a minimum and the preferred range of free fall distance is approximately 1/2 inch to 2 inches vertical drop.
I I
As mentioned previously, when the pills are removed from quenching solution 23 in tank 22, they are dried before being stored. The pills should be dried to a point where they contain less than 0.5% water by weight. At this point, the pills contain less moist lure than ambient air and therefore are super dry These super dry pills leaving the dryer 31, are screen-Ed into different sizes by conventional sizing screens 36 and are immediately packed in air-tight bags as if-lo lust rated at 37, or stored in humidity controlled bins for transportation and blending with other types of fertilizer.
It would therefore be appreciated that there has been described a process for the manufacture of a water-degradable Selfware product, which product is en-sentially dust free, is extremely durable due to the quenching process increasing the compressive strength thereof, and has good degradation characteristics once exposed to moisture in the soil.
Since various modifications can be made in my invention as hereinafter described, and many apparently widely different embodiments of same made within the spirit and scope of the claims without departing from such spirit and scope, it is intended that all matter contained in the accompanying specification shall be :;
31L;~L6~
interpreted as illustrative only and not in a limiting sense.
Claims
CLAIMS:
(1) A process for the manufacture of solid pellets or prills of a water-degradable homogenous sus-pension of bentonite in sulphur which gives the pellet or prill the required compressive strength whereby the crushing and swelling of the bentonite is inhibited during manufacture, handling and storage, comprising the steps of:
(a) Adding 1% to 15% by weight of substan-tially dry powdered bentonite to 99% to 85% of molten sulphur with continuous and thorough shear mixing in a tank at a temperature of between approximately 238°F and 318°F;
(b) Forming droplets of mixture;
(c) Providing a non-degrading quenching so-lution of a chloride or sulphate water mixture selected from the group con-sisting of sodium chloride, sodium sul-phate, potassium chloride and potassium sulphate, having a specific gravity bet-ween 1.001 and 1.08;
(d) Feeding said droplets into said quen-ching solution;
(e) Passing said droplets through said quenching solution for a time sufficient to anneal the droplets into prills;
(f) Removing said annealed prills from said solution, and, (g) Drying them at a temperature of between 150°F and 212°F to contain less than 0.5%
water by weight with the preferred water content to be less than 0.1% by weight.
(2) The process according to Claim 1 wherein said quenching solution is maintained at a temperature range in excess of 40°F up to approximately 100°F.
(3) The process according to Claim 1 which further includes the step of drying the prills with hot dry air after removal from the quenching solution to said water content of less than 0.5% by weight with the pre-ferred water content to be less than 0.1% by weight.
(4) The process according to Claim 2 which further includes the step of drying the prills with hot dry air after removal from the quenching solution to said water content of less than 0.5% by weight with the pre-ferred water content to be less than 0.1% by weight.
(5) The process according to Claim 1 wherein the droplet-forming step includes providing a removable tray having a matrix of holes created throughout.
(6) The process according to Claim 5 wherein the size of said holes is between approximately 3/64" to 7/64" with the preferred size being approximately 4/64".
(7) The process according to Claim 5 wherein the droplet-forming step further includes the step of providing a substantially constant pressure head of said mixture above said tray.
(8) The process according to Claim 7 wherein said pressure head is the range from approximately 1/2"
up to approximately 2".
(9) The process according to Claim 1 wherein the droplet feeding step includes allowing the droplets to freely fall from said tray to quenching solution.
(10) The process according to Claim 9 wherein the free fall distance is in the range of approximately 1/2" to approximately 2" vertical distance.
(11) The process according to Claim 1 in which the shear mixing temperature is maintained between ap-proximately 238°F and 318°F with the preferred tempera-ture being approximately 265°F.
(12) The process according to Claim 1 in which the bentonite contains montmorillonite prefer-ably in excess of 70% by weight.
(13) The process according to Claim 12 in which the powdered form of the bentonite is preferably of a size that between 95% and 98% will pass through 200 mesh U.S. Standard screen and of the remainder through a screen having a particle size of at least 80 mesh and preferably having at least 75% to 98% by weight of the powdered bentonite passing through a screen having a 325 mesh.
(14) The process according to Claim 12 in which the moisture content of the bentonite powder may exceed 3% by weight, but is preferably less than 3% by weight.
(15) The process according to Claim 13 in which the moisture content of the bentonite powder may exceed 3% by weight, but is preferably less than 3% by weight.
(16) The process according to Claim 1 which includes the additional step of adding a swelling-enhancing catalyst to the bentonite.
(17) The process according to Claim 1 in which the resultant prill size is between 1.0 mm and 5.0 mm diameter.
(18) A water-degradable solid prill product comprising a solid homogenous suspension of between 1% to 15% by weight of bentonite in sulphur, whenever prepared by the process of Claims 1, 2 or 3.
(19) A water-degradable solid prill product comprising a solid homogenous suspension of between 1% to 15% by weight of bentonite in sulphur, whenever prepared by the process of Claims 4, 5 or 6.
(20) A water-degradable solid prill product comprising a solid homogenous suspension of between 1% to 15% by weight of bentonite in sulphur, whenever prepared by the process of Claims 7, 8 or 9.
(21) A water-degradable solid prill product comprising a solid homogenous suspension of between 1% to 15% by weight of bentonite in sulphur, whenever prepared by the process of Claims 10, 11 or 12.
(22) A water-degradable solid prill product comprising a solid homogenous suspension of between 1% to 15% by weight of bentonite in sulphur, whenever prepared by the process of Claims 13, 14 or 15.
(23) A water-degradable solid prill product comprising a solid homogeneous suspension of between 1% to 15% by weight of bentonite in sulphure, whenever prepared by the process of Claims 16 or 17.
(1) A process for the manufacture of solid pellets or prills of a water-degradable homogenous sus-pension of bentonite in sulphur which gives the pellet or prill the required compressive strength whereby the crushing and swelling of the bentonite is inhibited during manufacture, handling and storage, comprising the steps of:
(a) Adding 1% to 15% by weight of substan-tially dry powdered bentonite to 99% to 85% of molten sulphur with continuous and thorough shear mixing in a tank at a temperature of between approximately 238°F and 318°F;
(b) Forming droplets of mixture;
(c) Providing a non-degrading quenching so-lution of a chloride or sulphate water mixture selected from the group con-sisting of sodium chloride, sodium sul-phate, potassium chloride and potassium sulphate, having a specific gravity bet-ween 1.001 and 1.08;
(d) Feeding said droplets into said quen-ching solution;
(e) Passing said droplets through said quenching solution for a time sufficient to anneal the droplets into prills;
(f) Removing said annealed prills from said solution, and, (g) Drying them at a temperature of between 150°F and 212°F to contain less than 0.5%
water by weight with the preferred water content to be less than 0.1% by weight.
(2) The process according to Claim 1 wherein said quenching solution is maintained at a temperature range in excess of 40°F up to approximately 100°F.
(3) The process according to Claim 1 which further includes the step of drying the prills with hot dry air after removal from the quenching solution to said water content of less than 0.5% by weight with the pre-ferred water content to be less than 0.1% by weight.
(4) The process according to Claim 2 which further includes the step of drying the prills with hot dry air after removal from the quenching solution to said water content of less than 0.5% by weight with the pre-ferred water content to be less than 0.1% by weight.
(5) The process according to Claim 1 wherein the droplet-forming step includes providing a removable tray having a matrix of holes created throughout.
(6) The process according to Claim 5 wherein the size of said holes is between approximately 3/64" to 7/64" with the preferred size being approximately 4/64".
(7) The process according to Claim 5 wherein the droplet-forming step further includes the step of providing a substantially constant pressure head of said mixture above said tray.
(8) The process according to Claim 7 wherein said pressure head is the range from approximately 1/2"
up to approximately 2".
(9) The process according to Claim 1 wherein the droplet feeding step includes allowing the droplets to freely fall from said tray to quenching solution.
(10) The process according to Claim 9 wherein the free fall distance is in the range of approximately 1/2" to approximately 2" vertical distance.
(11) The process according to Claim 1 in which the shear mixing temperature is maintained between ap-proximately 238°F and 318°F with the preferred tempera-ture being approximately 265°F.
(12) The process according to Claim 1 in which the bentonite contains montmorillonite prefer-ably in excess of 70% by weight.
(13) The process according to Claim 12 in which the powdered form of the bentonite is preferably of a size that between 95% and 98% will pass through 200 mesh U.S. Standard screen and of the remainder through a screen having a particle size of at least 80 mesh and preferably having at least 75% to 98% by weight of the powdered bentonite passing through a screen having a 325 mesh.
(14) The process according to Claim 12 in which the moisture content of the bentonite powder may exceed 3% by weight, but is preferably less than 3% by weight.
(15) The process according to Claim 13 in which the moisture content of the bentonite powder may exceed 3% by weight, but is preferably less than 3% by weight.
(16) The process according to Claim 1 which includes the additional step of adding a swelling-enhancing catalyst to the bentonite.
(17) The process according to Claim 1 in which the resultant prill size is between 1.0 mm and 5.0 mm diameter.
(18) A water-degradable solid prill product comprising a solid homogenous suspension of between 1% to 15% by weight of bentonite in sulphur, whenever prepared by the process of Claims 1, 2 or 3.
(19) A water-degradable solid prill product comprising a solid homogenous suspension of between 1% to 15% by weight of bentonite in sulphur, whenever prepared by the process of Claims 4, 5 or 6.
(20) A water-degradable solid prill product comprising a solid homogenous suspension of between 1% to 15% by weight of bentonite in sulphur, whenever prepared by the process of Claims 7, 8 or 9.
(21) A water-degradable solid prill product comprising a solid homogenous suspension of between 1% to 15% by weight of bentonite in sulphur, whenever prepared by the process of Claims 10, 11 or 12.
(22) A water-degradable solid prill product comprising a solid homogenous suspension of between 1% to 15% by weight of bentonite in sulphur, whenever prepared by the process of Claims 13, 14 or 15.
(23) A water-degradable solid prill product comprising a solid homogeneous suspension of between 1% to 15% by weight of bentonite in sulphure, whenever prepared by the process of Claims 16 or 17.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000458389A CA1216164A (en) | 1984-07-06 | 1984-07-06 | Process for forming prills from sulphur and bentonite |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000458389A CA1216164A (en) | 1984-07-06 | 1984-07-06 | Process for forming prills from sulphur and bentonite |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1216164A true CA1216164A (en) | 1987-01-06 |
Family
ID=4128261
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000458389A Expired CA1216164A (en) | 1984-07-06 | 1984-07-06 | Process for forming prills from sulphur and bentonite |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1216164A (en) |
-
1984
- 1984-07-06 CA CA000458389A patent/CA1216164A/en not_active Expired
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