WE CLAIM:

1. A process for preparing Cluster free slurry of Sulphur and Boron based fertilizer composition which is free from foaming- the process comprising of:
a) grinding anhydrous boron source more preferably the Anhydrous Disodium Tetra Borate to 150 micron size to match its bulk density with that of swelling material which is Bentonite powder,
b) mixing the said boron source raw material powder gradually with the swelling powder uniformly in a blender, and
c) adding the resultant mixture comprising of boron source powder & bentonite powder into the mixture of molten sulphur and bentonite at 1250C for preparing a uniform melt mixture, said melt mixture is a cluster free slurry easy to pastillate on steel belt on spraying by a rotoformer.
2. The process as claimed in claim 1, includes preparing a swelling powder in two portions, and mixing one of the two portions with molten sulphur at 1250C to prepare a uniform slurry and mixing the second portion of the swelling powder with anhydrous boron source powder to prepare a blend of powder materials.
, Description:FIELD OF THE INVENTION

The present invention relates to produce a cluster free and foam free melt mix while producing a fertilizer composition that include Sulphur mixed with any other nutrient like Boron and a swelling material like Bentonite.

BACKGROUND OF THE INVENTION:

Many technologies like prilling, granulation, extrusion, Pastillation, Pelletization, and Briquetting are available for producing a stable fertilizer forms. Selection of a technology depends on the properties of raw materials.

A process of solidifying the hot melt in the form of small drops on cold surface is termed as a pastillation. It is the most widely used technology in pharmaceutical and fertilizer industries to produce most stable forms.

Two or three different ingredients are mixed uniformly to a melt and solidified by this technique. The solid material of low melting point, with a higher composition in the final product can be chosen as a base material. The product formed by this technique will have low water content compared to other conventional granulation methods. It inherits the low or no hygroscopicity and hence low caking tendency.

A small group of particles formed with a liquid coating over it while mixing the solids with Sulphur melt is considered as cluster.

Cluster formation is the most undesirable thing which will affect the uniformity of the product while blending. The shear force of the melt cannot break the cluster.

To overcome the above, a process has been developed which produces a uniform cluster free melt consistently. Also the compatibility of different materials with the basic major component is discussed in detail.

PRIOR ARTS:

WO2016126278A1 disclosed fertilizer compositions with enhanced Sulphate release, methods of making the fertilizer compositions and methods of using the fertilizer compositions. It discloses the fertilizer compositions of elemental Sulphur with small amount of humic additive to enhance delivery of Sulphate to soil. The humic acid is added as a humic additive, which may comprise 40% or more humic acid. In many embodiments, the presence of small amount of humic additive enhances the release of Sulphate from soil containing the fertilizer composition from about 1.5- to 4-fold over fertilizer compositions lacking the humic additive. It is different from our invention because it does not related to bentonite Sulphur pastilles formation with other nutrients like Boron.

US patent US6331193 B1by Robin Phinney, filed on 17 Apr 1998 and published on 18 Dec 2001, with the title “Wet granulation method generating sulfur granules” presents a method of wet granulation of sulfur powder having about 99.9% particle size of -150 mesh and a binder material to form a pre-moistened mixture with moisture content of between 4% and 8% by weight and feeding pre-moistened mixture to a pan granulator containing sulfur powder. It is different from our invention because doesn’t involve pastillation on cold surface & preparation of melt mixture suitable for pastillation.

US patent US 4,394,150 Explains globular granules of Sulphur-bentonite fertilizer having a mixture of 88-89% of Sulphur and 11—12% of bentonite and in this process the granules are formed by mixing ground down bentonite with liquid Sulphur and dropping liquid mixture passed through holes in the bottom of tank containing the mixture, while drops are solidified into granules in liquid manure salt solutions and dried. It is different from our invention because it doesn’t involve pastillation on cold surface & preparation of melt mixture suitable for pastillation.

Europe patent EP2081878 A2 by Zaklady Chemiczne, filed on 20st Aug 2007 and published on Jul 29, 2009, with the title “Sulphur fertilizer and granulated Sulphur fertilizer manufacturing method” discusses Sulphur fertilizer, in form of globular granules or pellets consists solidified mixture of liquid Sulphur, bentonite and SLS. In its solidified mixture, the fertilizer contains 60-95% of Sulphur, 4-20% of bentonite, and 1-8% of SLS. In this method mixture of liquid Sulphur with bentonite and SLS is splashed into the granulator at 120-150° C to form droplets, it forms a curtain of falling granules and solidified by passing air through the curtain of granules. It is different from our invention because it doesn’t involve pastillation and problems there in.

Canadian patent CA1054821 A1 by Bob L. Caldwell, Canadian Superior Oil Ltd., filed on Sep 17, 1975 and published on May 22, 1979 titled “Granular sulfur-bentonite mixture for fertilizer” elaborates a method for manufacture of a WDG solid suspension of elemental Sulphur in bentonite clay, comprising addition of 1 to 3 parts bentonite to 7 to 9 parts of molten Sulphur, and mixing at 240 and 300°F., pouring the uniform mixture onto a wet thermally conductive metal plate, and to cool to a thickness of 1/4 to 2 inches, reducing size and separating granules size of minus 4/plus 14 mesh on the U.S. Standard scale. It is single nutrient and does not discuss on a second nutrient addition and preparation of cluster free melt while mixing the second nutrient.

US Patent 109639 with tittle FERTILIZER COMPOSITION CONTAINIG SULPHUR AND BORON discuss about the method of manufacturing a fertilizer composition containing Sulphur and boron, the method comprising mixing boron containing compound with molten Sulphur followed by swelling material. It focuses on desiccating the boron containing compound to reduce moisture content. It also covers the percentage addition of boron and other micro nutrient sources based on the requirement. It specifically mentioned that Di sodium borate is used as boron source. It does not discuss on preparation of suitable melt mix to avoid cluster formation in the process where as that our focus of invention is preparation of cluster free melt hence different from this patent. Even though pastillation of bentonite Sulphur is a prior art the method of adding Boron as another nutrient to form a cluster free melt is our invention.

OBJECT OF THE INVENTION

The main object of the invention is to develop a process to achieve a uniform, cluster free and foam free melt mix for the manufacture of a fertilizer composition with boron and Sulphur. The physical and chemical properties of raw materials will control the degree of uniformity of melt mix. The object is to disclose a process by which the uniformity is achieved more than that in prior arts.

The second object is to disclose a process by which cluster free Boronated bentonite Sulphur melt can be prepared for easy pastillation.

Another object of the invention is match the compatibility of boron source with molten Sulphur and the Bentonite used as swelling material.

One more object of the invention is to specify the range of bulk densities of boron source at which uniformity of mixing is achieved.
Description of Drawings:

Figure 1

Legend :
1. Boron source 7. Blending
2. Material size distribution 8. Sulphur melt
3. Over size 9. Melting tank
4. Pulverizer 10. Steam
5. Preferred size 11.Pastillation
6A & B. Bentonite clay

Detailed Description:

The present disclosure provides a process for the production of a cluster free melt mix when a fertilizer composition that includes sulfur mixed with any other nutrient source and a swelling material.

In one aspect, the invention discloses a process for preparing sulphur and Boron based fertilizer composition comprising of following steps:

a) Anhydrous Disodium Tetra Borate is ground to 150 micron size to match its bulk density with that of the swelling material i.e Bentonite powder.
b) The Boron source raw material powder is then mixed with swelling material i.e Bentonite powder uniformly in a blender. The resultant mixture of Boron substance and Bentonite powder are added in to the slurry of molten Sulphur + Bentonite powder at 1250C and preparing a uniform melt mixture

The said melt mixture forms cluster free slurry with uniform composition with no difficulties of separation by settling or floating and is also free from foaming tendency which occurs in other methods of making the slurry. The said melt mixture is easy to pastillate on steel belt on spraying by the rotoformer.

The inclusion of born sources with molten Sulphur have a serious difficulties. For example adding a Boron containing compounds to the molten Sulphur and bentonite mixture causes rapid foaming and may come out of the melting tank. The challenge is to find out the compatible substance and size of boron source. After conducting many experiments a final Process Flow Diagram is developed for cluster free mixing of the melt containing Sulphur, Bentonite and boron source material. PFD is given as Fig.1 .The details of the experiment conducted are described below.

Experiments are conducted with four different boron materials
1. Boric acid
2. Di sodium Octa borate Tetra hydrate 200 mesh
3. Anhydrous Di Sodium Tetra borate 32 mesh
4. Anhydrous Di Sodium Tetraborate crushed to 100 mesh

Experiment 1:

Boric acid consisting of 16% of boron is used as a boron source in this experiment. Bentonite material is first mixed with the molten Sulphur at 125 deg C in a melting tank, after confirming the uniformity of the mixture a small amount of boric acid is added to it, rapid foaming is observed from the experimental melting tank. Fig.2 is the foam coming out of the tank and Fig.3 is the foam after solidification. Boric acid is combining with the bentonite and getting separated from the molten Sulphur as foam. Therefore it is not suitable to our process.

Experiment 2:

Disodium Octa borate tetra hydrate of 200 mesh with 3% moisture is used as a born source. Bentonite material is first mixed with the molten Sulphur at 125 deg C, after confirming the uniformity of the mixture a small amount above mentioned material is added. After 30 min of mixing small clusters of the borate is observed. Fig 4A and 4B are the cluster formation of borate after 30 minutes of continuous mixing. Clusters are analyzed in laboratory and confirmed that it contains 90% boron. Here the Boron powder is getting separated from Sulphur melt as clusters. Disodium Octa borate tetra hydrate contains 4 water molecules in its crystal structure which accounts to 17% as bound moisture. Water activity of boron containing compound affects the uniformity of the melt.

Experiment 3:

Disodium Octa borate tetra hydrate of 200 mesh size is Pre-heated to remove both free moisture and crystal moisture and then mixed with the melt. This way it did not give cluster formation. Fig 5.0 indicates the uniformity in the final melt after cooling.

Experiment 4:

To avoid pre heating step of Disodium Octa borate tetra hydrate, Anhydrous Di sodium tetra borate of 32 mesh size is taken as a boron source. Bentonite is first mixed with the molten Sulphur at 125 deg C, after confirming the uniformity of the mixture a small amount anhydrous Di sodium tetra borate is added. No cluster or foaming observed. Melt sample taken from different heights of tank and solidified on a cold surface. After cooling the melt it is observed that there is a separation of Boron from Sulphur melt. Fig. 6.0 clearly indicates the scenario.

Checked the bulk densities of Bentonite, Anhydrous Di sodium tetra borate of 32 mesh size were checked and found to be different, noted that the separation of material is due to difference in the densities of materials. To avoid this kind of separation, we have reduced the particle size of the anhydrous boron to the extent by which it matches with the bulk density of the swelling material.

Fig.7 represents the detail bulk density study of the anhydrous Di sodium tetra borate which is ground to different particle sizes and compared with the bulk density of the Bentonite.

Bulk density of anhydrous Di sodium tetra borate is measured at different particle sizes. Batches of 32 mesh anhydrous borate is crushed in a hammer mill till 36 mesh, 72 mesh and 100 mesh.

Bulk density of the third batch containing = 80% 100 mesh size is matching with the bulk density of the bentonite clay.

Example 5:

We have conducted a pilot scale experiment of 100 kg anhydrous Di sodium tetra borate with 80% -100 mesh size. Bentonite material is first mixed with the molten Sulphur at 125 deg C, after confirming the uniformity of the mixture the above anhydrous Di sodium Tetra borate 100 mesh size is added slowly. After 30 min of mixing melt sample is taken for analysis.

Tiny clusters are observed even with particle size reduction of anhydrous boron. It is observed that crushed anhydrous Di sodium tetra borate is picking up the moisture and results in tiny clustering.
Example 6:

To avoid formation of tiny clusters, we mixed the crushed (ground to 150 micron size) Anhydous Tetra Borate with Bentonite material and added slowly with the Molten Sulphur + Bentonite slurry and mixed thoroughly by running the agitator. This time the melt is uniform and the pastilles that obtained are also meeting the specifications. the same experiment is repeated in a process plant of 5MT batch and successfully reproduced the results.Fig.9.0 is the uniform melt mix obtained in 5MT batch.

Finally it is concluded that cluster free mix was formed.

The essential inventive step of the invention lies with the process for preparing sulphur based fertilizer composition comprising of

a) Making the required quantity of swelling material in to two parts and mixing one part of swelling material with molten sulphur at 1250C and preparing a uniform slurry
b) crushing the Anhydrous Boron substance in to 150 micron size powder
c) thorough mixing of the second part of Swelling material to the Anhydrous boron source ground to 150 micron by step (b) to form a uniform blend
d) then slowly adding and mixing thoroughly the blend of swelling material and anhydrous Boron source prepared in step (c) to the uniform slurry of molten Sulphur + swelling material formed in step(a) such that the prepared composition is a boronated Bentonite sulphur based fertilizer with cluster free boron content.

Further this process selected bentonite as swelling material and the anhydrous boron source selected as. Furthermore this process selected anhydrous DiSodium tetra borate crushed to 150 micron size powder as Boron source.

The examples and embodiments are provided only for the purpose of understanding and none of them shall limit the scope of the invention. All variants and modifications as will be envisaged by skilled person are within the spirit and scope of the invention.