DESC:*** Complete Specification ***

“High density graphite briquettes and method of manufacturing the same”

Cross references to related applications: This complete specification is filed further to application for patent No. 202231069737 filed on 02/12/2022 with provisional specification, the contents of which are incorporated herein in their entirety, by reference.

Reference to sequence listing, a table, or a computer program listing compact disk appendix: Not Applicable

Field of the invention
This invention belongs to the field of high-density reducer products and processes for manufacturing said products from carbon. Specifically, the disclosures hereinunder propound a high-density graphite briquette, a method to prepare said briquette, and application of said briquette as a carbon additive in iron and steel industry.

Definitions
Before undertaking the description of the invention below, it may be advantageous to set forth definitions of certain words or phrases used throughout this patent document. Also, as some technical terms are not used uniformly in the field of the instant invention, a few definitions are given in the following to clarify the meaning of terms as they are used in this paper. Accordingly, the following terms shall mean and refer, as under-

“Briquette” refers to a compressed block of graphite material used as reducers in the smelting process of Steel making.
“Recarburizer” refers to agent capable of introducing carbon into molten steel / iron, in order to adjust carbon levels in the manufacturing of steel / iron, used synonymously herein to “carbon additive”, “carbon raiser” and / or “charge carbon”.
“GPC” refers to Graphitized Petroleum Coke.

Background of the invention and description of related art
As defined in the foregoing section, recarburizers are required in the manufacturing of steel / iron, particularly for introducing carbon into molten steel / iron, in order to adjust carbon levels as desired in the final steel / iron output. Petroleum coke, natural graphite and synthetic graphite are popular recarburizers used in the industry.

Graphite is recognized as one of the environment-friendly recarburizers used in the metallurgical industry, and tops the popular choices among conventionally available recarburizers due to its inherent attributes including soft material, low sulfur content, low nitrogen content, high absorption rate, good lubrication, good fluidity, can be injected directly into furnace, generates no blasting ashes, and absence of odors.

Due to the aforementioned advantages, there is a large global demand for graphite in the metallurgical industry. Natural-graphite and finely ground artificial-graphite powders have been thus applied as recarburizers. In this line, it shall be advantageous to have some strong, compact, dense form of graphite which-
a) Encourages high carbon absorption into the melt.
b) Exhibits good, uniform and quick solubility into the melt.
c) Is easy for introduction into the melt.
d) Lends favorably to storage, transport and use.

In general, briquetting improves the handling characteristics of the reducing material, increases the volumetric value, and makes it available for a variety of applications. The reducing material may include petroleum coke, natural graphite and synthetic graphite.

Compacting / shaping methodologies for packaging of natural-graphite and / or finely ground artificial-graphite powders find mention in the art. For example, R. H. De Vere et al, (The Briquetting Of Graphite, Powder Metallurgy, 6:11, 23-41, Published on 05 Nov 2014; DOI: 10.1179/pom.1963.6.11.002) explores compacting of graphite and the relation of particle size and size distribution on compaction quality and strength of resultant briquettes. An empirical relationship S = KA 5/2 is reported in this paper, as being between the strength (S) and the specific surface area (A) of the powder, was obtained for electro-graphite powder compacted at 10 tons/in2.

However according to the applicant named herein, the state of art has certain unaddressed lacunae which hence have become objectives for further research, and which have thus resulted into the invention subject hereof. And, while there were many common art references researched by the applicant in ensuring that the present invention is novel and inventive, no prior art, to the limited extent presently surveyed, did not list a single effective solution per-se, thus preserving the necessity for the present invention.

A better understanding of the objects, advantages, features, properties and relationships of the present invention will be obtained from the following detailed description which sets forth an illustrative yet-preferred embodiment.

Objectives of the present invention
The present invention is identified in addressing at least all major deficiencies of art discussed in the foregoing section by effectively addressing the objectives stated under, of which:

It is a primary objective to establish a standardized method for preparing high-density graphite briquettes.

It is an objective further to the aforesaid objective(s), that the briquettes so prepared lend favourably for introduction into the melt, wherein they exhibit good, uniform and quick solubility and higher carbon absorption into the melt.

It is an objective further to the aforesaid objective(s), that the briquettes so prepared are sufficiently dense and compact,

It is an objective further to the aforesaid objective(s), that the briquettes so prepared lend favorably to storage, transport and use.

It is an objective further to the aforesaid objective(s), that the manufacturing method so established is inexpensive to implement.

It is an objective further to the aforesaid objective(s), that the manufacturing method so established has no stringent dependencies as to the raw materials and other process inputs.

It is an objective further to the aforesaid objective(s), that the manufacturing method so established has a high throughput in minimal time.

It is an objective further to the aforesaid objective(s), that the manufacturing method so established is easy to implement for even a layman belonging to the field of this invention.

The manner in which the above objectives are achieved, together with other objects and advantages which will become subsequently apparent, reside in the detailed description set forth below in reference to the accompanying drawings and furthermore specifically outlined in the independent claims. Other advantageous embodiments of the invention are specified in the dependent claims.

Statement of the invention
The present invention is identified in the production of high-density graphite briquettes which are made by compressing graphite particles together to form a cohesive and dense structure, in an approach to Increase density of agglomerate using a higher density fiber or material.

A better understanding of underlying principles of the present invention will be obtained from the following elaboration which sets forth an illustrative yet-preferred embodiment of the present invention.

Detailed Description
The present invention is directed at absorbing all advantages of prior art while overcoming, and not imbibing, any of its shortfalls, to thereby establish a high-density graphite briquette, a method to prepare said briquette, and application of said briquette as a carbon additive in iron and steel industry.

A yet-preferred embodiment of the present invention is described hereunder, which is directed at the manufacturing of briquettes of more than 2 g/cc density to 5 g/cc for use in the iron / steel industry. For making said briquettes, an inventive methodology is established herein, to be implemented by performing the following sequence of steps-
a) Suitable compactable material is subjected to a preconditioning process including drying, grinding, and sieving to obtain preconditioned compactable material.
b) A whisker forming material and optionally a binder (dextrin), are added to the preconditioned compactable material to form a dense and heavy coarse admixture.
c) Compacting the coarse admixture using a die to result in the final briquettes of this invention.

The step of preconditioning mentioned in step a) above includes drying of the compactable material using either among a rotary dryer, wire mesh dryer, vertical dryer, sun drying, resulting in a dried mass containing less than 1% moisture; Grinding the dried mass using a roller crusher to result in fines; and sieving the fines using sieves of suitable pore size to obtain fine preconditioned material having an average particle size including and ranging between 0.01 mm to 5 mm.

In the aforementioned step b) of preparing the dense and heavy coarse admixture, admixing of ingredients is undertaken in the specific proportion reflected in Table 1 below-
Sr. No. Ingredient Relative proportion (w/w)
(a) Compactable material 50% to 80%
(b) Whisker forming material 0.01% to 47%
(c) Binder 0% to 3%

Table 1

When prepared by the aforementioned methodology, the fibers form whiskers in- between which the fines get haphazardly entrapped and compressed. Furthermore compacting is arranged in step c) of compacting wherein briquetting is undertaken using a die with a hydraulic type briquetting machine having 5 MT to 25 MT roll separating force.

According to a related aspect, the whisker forming material is chosen as wires of metal chosen among steel, manganese, aluminum, their equivalents, their alloys and their combinations. Further embodiments of the present invention can well be implemented with non-metallic whiskers, without departing from the essence of the present invention.

According to another related aspect, the fibers of the whisker-forming material are characterized in having an average cross-sectional thickness including and ranging between 0.3 mm to 1 mm and length including and ranging between 3 mm to 15 mm for optimum effect as mentioned above.

As mentioned above, the fibers form whiskers in- between which the fines get haphazardly entrapped and compressed. The resultant structure thus becomes dense and heavy, due to which when these briquettes are charged, they dip to the slag metal interface where the material of whiskers (especially if metal) melts and the carbon particles open up. These small carbon particles do not have the buoyancy to break the surface tension of viscous slag and so they remain in the slag metal interface where the carbon is absorbed by the steel, with a higher recovery rate.

Hence, the briquettes prepared in accordance with this invention are easy for introduction into the melt, exhibit good, uniform and quick solubility into the melt, and exhibits higher carbon absorption into the melt. Being dense and compact, the briquettes prepared in accordance with this invention lend favorably to storage, transport and use.

As known in the art, the density of slag is approx. 2 g/cc, which is why the briquettes produced as per the foregoing narrative, when charged into slag, sinks into the slag metal interface where it has no air to oxidize but left with option of picking up in the steel.

According to one aspect hereof, the compactable material used herein is chosen between fines of graphite, calcined petroleum coke, anthracite, their equivalents and their combinations, having a particle size range between 0.01 mm to 5 mm.

In alternative embodiments hereof, Magnesium and aluminium fines can be alternatively used, where the output material is to be lighter than the slag. Process methodology remains the same as mentioned in the foregoing part of this description.

According to another aspect hereof, the metal fibers used herein are of steel in particular.

From the foregoing narration, an able technology for briquetting of graphite and other fines is thus provided with marked novelty, inventive contribution, and industrial applicability than any background and / or prior art, which is furthermore typified in having the following salient features-
a) Capability of working with fines having lower agglomeration characteristics which are otherwise difficult to briquette/ agglomerate
b) Minimizing / Avoiding the requirement of binders, and thus ensuring fume free, carbon release into the melt

Industrial applicability
High-density briquettes, as produced by the methodology of this invention, find ready applicability at industrial scale in various applications, especially in the field of metallurgy and manufacturing. The high density of these briquettes makes them suitable for use in applications where durability and high absorption rate are essential.

Cost effectiveness
Conventionally, if the price of GPC lumps is X then cost of carbon fines is 0.7 X. Cost of briquetting is 0.5X. The yield is 60% for GPC lumps and 90% for briquettes. Steel fibres go cost to cost into the steel, hence do not burden the economics of the process. Hence, the reader shall appreciate that the high-density briquettes, as produced by the methodology of this invention, are truly cost-effective to produce and use.

As will be realized further, the present invention is capable of various other embodiments and that its several components and related details are capable of various alterations, all without departing from the basic concept of the present invention.

Accordingly, the foregoing description will be regarded as illustrative in nature and not as restrictive in any form whatsoever. Modifications and variations of the system and apparatus described herein will be obvious to those skilled in the art. Such modifications and variations are intended to come within ambit of the present invention, which is limited only by the appended claims. ,CLAIMS:1) A method for preparing high-density graphite briquettes, comprising-
a) Selecting a suitable compactable material for briquetting;
b) Subjecting the compactable material selected to a preconditioning process to obtain fine preconditioned material for briquetting;
c) Admixing with the fine preconditioned material and a suitable whisker-forming material, to form a dense and heavy coarse admixture resulting from the in-situ formation of whiskers around which the fine preconditioned material gets haphazardly entrapped and compressed; and
d) Compacting the dense and heavy coarse admixture to form the final high-density briquettes being ready for use.

2) The method for preparing high-density graphite briquettes as claimed in claim 1, wherein the suitable compactable material is selected from among fines of graphite, calcined petroleum coke, anthracite, their equivalents and their combinations.

3) The method for preparing high-density graphite briquettes as claimed in claim 2, wherein the suitable compactable material is characterized in having a particle size range including and ranging between 0.01 mm to 5 mm.

4) The method for preparing high-density graphite briquettes as claimed in claim 1, wherein the suitable whisker-forming material is selected from among fibers of metal chosen among steel, manganese, aluminum, their equivalents and their combinations.

5) The method for preparing high-density graphite briquettes as claimed in claim 4, wherein the fibers are selected as those having an average cross-sectional thickness including and ranging between 0.3 mm to 1 mm and length including and ranging between 3 mm to 15 mm.

6) The method for preparing high-density graphite briquettes as claimed in claim 1, wherein the step b) includes admixing of ingredients in the specific proportion selected among-

a) 50% to 80% w/w of the fine preconditioned material; and
b) 20% to 50% w/w of the suitable whisker-forming material.

7) The method for preparing high-density graphite briquettes as claimed in claim 1, further including in step b), adding 0% to 3% w/w of a binder, dextrin in particular, for augmenting the agglomeration of the dense and heavy coarse admixture.

8) The method for preparing high-density graphite briquettes as claimed in claim 1, wherein the preconditioning process consists of the serial implementation of certain steps, consisting of-
a) Drying the compactable material selected, using either among a rotary dryer, wire mesh dryer, vertical dryer, sun drying, resulting in a dried mass containing less than 1% moisture;
b) Grinding the dried mass using a roller crusher to result in fines;
c) Sieving the fines using sieves of suitable pore size to obtain fine preconditioned material having an average particle size including and ranging between 0.01 mm to 5 mm.

9) The method for preparing high-density graphite briquettes as claimed in claim 1, wherein the step d) of compacting is undertaken using a die with a hydraulic type briquetting machine having 5 MT to 25 MT roll separating force.

10) The high density graphite briquette prepared by the method of claim 1 being characterised in-
a) Being made from fines having lower agglomeration characteristics;
b) Having an average density ranging from 2 gm/cc to 5 gm/cc.
c) Minimal if at all of any binders; and
d) Increased density of agglomerate using a higher density fiber or material