Description:FORM 2
THE PATENT ACT 1970
(39 OF 1970)
&
The Patent Rules, 2003
COMPLETE SPECIFICATION
(See Section 10 and Rule 13)

1 TITLE OF THE INVENTION :
A PROCESS FOR RECOVERY OF CARBON AND REMOVAL OF ALKALI FROM THE BLAST FURNACE POT DUST.



2 APPLICANT (S)

Name : JSW STEEL LIMITED;

Nationality : An Indian Company.

Address : Dolvi Works, Geetapuram, Dolvi, Taluka Pen, Dist. Raigad, Maharashtra-402107,India; Having the Registered Office at
JSW CENTRE,BANDRA KURLA COMPLEX,BANDRA(EAST), MUMBAI-400051, STATE OF MAHARASHTRA, INDIA.




3 PREAMBLE TO THE DESCRIPTION

COMPLETE

The following specification particularly describes the invention and the manner in which it is to be performed.

FIELD OF THE INVENTION
Present invention relates to a process for recovery of carbon and removal of alkali from blast furnace pot dust for rendering it suitable for recirculating in steel plant operations including as input in sinter/ pellet/ briquette plant. More particularly, the present invention is directed to a process involving selected parameters for froth floatation followed by water leaching and filtration for recovering carbon as a carbon rich froth, subjecting non froth to water leaching and filtering the leach solution to obtain solid residue substantially free of alkali and sulfur to make it suitable for use in steel plant operations including sintering process, while the filtrate solution is evaporated and crystallized for getting alkaline salts as a separate product and recycling water after condensation.
BACKGROUNDOF THE INVENTION
The dust collected from the off gas of the blast furnace is considered as one of the major solid wastes generated in the steel industries. Recently, dry de-dusting of the BF top gas has gained popularity due to the high energy saving potential (high pressure and temperature of the cleaned gas leading to the generation of power) and lesser environmental emissions. Dry de-dusting systems comprises of two-stage air classifiers. The primary air classifier generally captures coarse particles, whereas the secondary classifier mainly catches fine to ultrafine particles. This particular type of secondary dust is commonly referred to as "pot dust," and it is generated in substantial quantities, necessitating its consumption within the steel sector. Typically, the production of one ton of raw steel generates approximately 20-40kg of BF dust. Pot dust contains various valuable constituents like iron, coal, calcium oxide and magnesium oxide, which needs to be recirculated to the mainstream for iron making applications. However, the presence of detrimental components like alkali and sulphur imposes limitations on its recirculation by adversely affecting the blast furnace operations.
It is widely recognized that BF dust, particularly its finer fraction, contains a significant amount of alkali metals. These metals have numerous adverse effects on blast furnace operations. These effects include higher coke consumption, premature softening of the ore charge, decomposition of sinter, swelling of pellets, formation of scaffolds, and damage to refractory materials. Moreover, the pot dust is commonly used in the sinter plant, which is reported to form fused mass in the grate bars causing grate bar jamming, which hampers sinter production. Consequently, the removal of these impurities from the pot dust, followed by its recirculation, could offer substantial benefits to the iron and steel industries from both economic and environmental prospective. Quantitatively speaking, reducing alkali input by 1 kg/ton of hot metal in blast furnace reduces the coke rate by approx. 10 kg/ton of hot metal, which has a significant impact on CO2 emission as well as cost of the steel production.
When these solid wastes (typically of the order of 200-300 tons/day) are added in the pellet mix (typically of the order of 10,000-25,000 tons/day), uniform mixing extremely difficult due to the limitations available time and intensity of mixing prevailing in the industrial process. Pot dust contains Carbon and if there is a non- uniform mixing of Carbon in the pellet green mix, it affects the pellet quality significantly causing inconsistent pellet quality.
Literature reports the use of technologies like gravity concentration, magnetic separation, froth flotation, and leaching for the processing of the pot dust. However, the existing technologies offer complex processing circuit as well as produces secondary pollutants. Thus, it is the need of the hour to develop a simple and comprehensive processing technique that can be implementable for the utilization of these solid wastes.
Some relevant patent documents in the same field discussing the state of prior arts are summarized below:
Patent no. CN103966421A, entitled as “A method for comprehensive recycling of iron and steel metallurgical waste” presents a technique for mitigating alkali content in diverse solid waste materials produced by the iron and steel sectors. This method involves the utilization of water-based leaching, followed by a subsequent crystallization procedure. The resulting leachate is subjected to treatment with Na2S and K2SO4 to eliminate impurities. Subsequent steps include concentration through evaporation and crystallization to recover KCl as a secondary product. To attain a product rich in Fe values, a magnetic separation technique is employed. The non-magnetic fraction is subsequently subjected to roasting at a temperature of 1200°C to acquire values of directly reduced iron. Additionally, the process encompasses the extraction of metallic zinc from zinc-containing fumes through leaching, purification, and electro-winning methodologies.
Patent no CN103435073B, entitled as “Method for producing potassium chloride by using blast furnace dust of iron and steel enterprises” outlines a technique for generating KCl from the residual matter of blast furnaces. While this patent does not explore the recirculation of the material into the iron making process, it concentrates on the treatment of solid waste and extracting a valuable secondary product. This methodology encompasses a two-stage process involving water leaching, subsequent filtration, and evaporation crystallization. To eliminate impurities before the evaporation crystallization stage, sodium carbonate, sodium sulfate, and potassium sulfate are employed as precipitating agents.
Patent no CN105712380A, entitled as “System and method for production of potassium chloride sintering flue gas precipitator dust’ discloses the art of extracting potassium chloride salt through a sequence of water leaching, precipitation, and evaporation crystallization procedures. In this method, a concentrated KCl solution acts as the precipitating agent and the solution is subjected to heating at temperatures ranging from 85°C to 95°C to achieve super-saturation. Subsequently, solid crystals are separated from the solution via filtration, resulting in the production of KCl crystals characterized by high purity levels.
Patent no CN113403480A, entitled as “Recovery method and application of high alkali high zinc blast furnace gas ash” reports the dealkalizing and dezincification of blast furnace gas ash along with their respective processes. The elimination of alkali from blast furnace gas ash is executed through a multi-stage water leaching process, with the recovered alkali subsequently processed via evaporation crystallization. The de-alkalized gas ash is subsequently subjected to a carbothermic reduction process, resulting in the generation of secondary ZnO powder. This powder is then subjected to leaching using a leaching reagent containing ammonia. Following this, the solution containing the zinc-ammonia complex undergoes ammonia-evaporation crystallization, culminating in the production of zinc carbonate crystals.
OBJECTS OF THE INVENTION
The basic object of the present invention is directed towards developing a simple and comprehensive technology for recovering iron and removal of alkali from the blast furnace flue dust and recirculating the residue product using physio-chemical and hydrometallurgical processing routes involving froth floatation, water leaching and filtration.
A further object of the present invention is directed to a processing route that can produce a carbon rich froth, de-alkalized product which can be used as input in sinter/ pellet/ briquette plant, and alkali can be a separate marketable byproduct for the variety of application including but not limited to the fertilizer, cement, chemical reagents manufacturing etc.
A still further object of the present invention is directed to a process of removal of alkali from pot dust that can help in avoiding major industrial problems such as jamming of grate bars in the sinter plant, increase in coke rate, scaffolding and raw material degradation in blast furnace.
A further object of the invention is to provide a process wherein Carbon is separated prior to the leaching process in order to reduce the load on the leaching tank. Further, the separation of carbon is also important in order to avoid the accumulation of these particles in sinter/pellet making, which can increase the local temperature in the sinter/pellet bed and subsequent detrimental effects.
It is important to separate Carbon from the pot dust which could be added alongwith the regular coal/coke input, so that uniformity of mixing can be improved and deteriorating effect on the consistency of the pellet quality can be avoided.
The separated carbon particles could be consumed either in the same pelletization process through a different route or in various other iron or steel making applications. Notably, reducing alkali input by 1 kg/ton of hot metal in blast furnace reduces the coke rate by approx. 10 kg/ton of hot metal which reduces 12 kg/ton CO2 emission.
SUMMARY OF THE INVENTION
The basic aspect of the present invention is directed to a process for the recovery of carbon and removal of alkali from the blast furnace flue/pot dust for rendering it suitable for recirculating in steel plant operations including as input in sinter/ pellet/ briquette plant comprising the steps of
(i) Step 1: separating the carbon bearing particles and thereby recovering carbon by Froth flotation of pot dust comprising
(a)Subjecting the dry pot dust to the flotation cell with water maintaining a pulp density of 30-40%;
(b)Dosing Diesel oil with the dosage of 200-300 g/ton as collector;
(c)Dosing Methyl isobutyl carbinol (MIBC) with dosage of 50-100 g/ton as frother;
(d)filtering and drying the floated froth to thus recover a high purity carbon rich product;
(ii) Step 2: removal of alkali from the non-froth portion of pot dust pulp obtained in step 1 by leaching with water for the dissolution of alkali content and subjecting to filtration thereby producing solid residue substantially free of alkali content which is suitable for reuse in iron making such as in sinter/pellet/briquette making plant.

A further aspect of the present invention is directed to said process comprising the step of processing the leach liquor from said step of alkali removal for recovery of valuable solid residue rich in different salts including selectively Na2SO4, K2SO4, KCl, NaCl following:
I) subjecting the leach liquor to Crystallization and extraction of salts therefrom by evaporation comprising
(a)Heating the leach liquor gently to allow the water to evaporate, to thereby increase the concentration of salt in the solution ;
(b)Allowing the crystals of various salts to precipitate gradually;
(c)Filtering the precipitate to separate the solid residue containing different salts (Na2SO4, K2SO4, KCl, NaCl) for use as separate marketable byproduct for the variety of application including but not limited to the fertilizer, cement, chemical reagents manufacturing etc.
II) Condensation of evaporated water for reusing it as make up water in the floatation or leaching process.

A still further aspect of the present invention is directed to said process for the recovery of carbon and removal of alkali from the blast furnace flue/pot dust for recirculating the residue product in steel plant operations including as input in sinter/ pellet/ briquette plant comprising
physio-chemical and hydrometallurgical processing for separation of carbon and alkali involving the steps of
(i) Step 1: separating the carbon bearing particles by Froth flotation of pot dust comprising
(a)Subjecting the dry pot dust to the flotation cell with water maintaining a pulp density of 30-40% and maintaining impeller speed constant at 1500 rpm;
(b)Dosing Diesel oil with the dosage of 200-300 g/ton as collector and conditioning for 5 min;
(c)Dosing Methyl isobutyl carbinol (MIBC) with dosage of 50-100 g/ton as frother and conditioning for 2 min;
(d) filtering and drying the floated froth to obtain a high purity carbon rich product;
(ii) Step 2: Leaching of non-froth portion of pot dust pulp obtained in step 1 with water for the dissolution of alkali content comprising
(a) subjecting the dry pot dust to leaching in the leaching tank with water maintaining a pulp density of 30-40%;
(b) agitating the solution with the help of a mechanical stirrer for 30-45 min maintaining temperature of the pulp at 80-950C preferably 900C; and
(c) subjecting the leached solution to filtration.
(iii) Step3: Filtration comprising
(a) filtering the solution present in the leaching tank using a filter press;
(b)The solid residue obtained having low alkali content is dried, making it suitable for reuse in iron making such as in sinter/pellet/briquette making plant.
(iv) Step4: subjecting the leach liquor to Crystallization and extraction of salts therefrom by evaporation comprising
(a)Heating the leach liquor gently to allow the water to evaporate, to thereby increase the concentration of salt in the solution;
(b)Allowing the crystals of various salts to precipitate gradually;
(c)Filtering the precipitate to separate the solid residue containing different salts (Na2SO4, K2SO4, KCl, NaCl) for use as separate marketable byproduct for the variety of application including but not limited to the fertilizer, cement, chemical reagents manufacturing etc.
(v) Step 5: Condensation of evaporated water for reusing it as make up water in the floatation or leaching process.
A still further aspect of the present invention is directed to said process wherein said leaching step comprising water leaching of pot dust at a temperature of 80-950C for 60minutes.
A still further aspect of the present invention is directed to said process wherein the filtrate obtained in said filtration step is evaporated gently leading to super-saturation of the solution whereby the gradual increase in concentration over time initiates the crystallization and precipitation process.
A still further aspect of the present invention is directed to said process wherein the solid residue obtained after filtering the leached solution has lower sulfur content suitable for use in sinter plant.
A still further aspect of the present invention is directed to said process wherein the filter residue is air-dried or subjected to hot air for drying.
Another aspect of the present invention is directed to said process wherein the elemental composition of pot dust used as raw material input comprises
Constituents Na2O MgO Al2O3 SiO2 SO3 Cl K2O CaO P2O5 TiO2 Fe ZnO PbO C
% 1.5 0.9 3.6 7.0 3.2 1.5 3.5 5.6 0.1 0.2 30.9 1.4 0.1 26.9

Yet another aspect of the present invention is directed to said process wherein froth is enriched to 83% of total carbon content with an overall recovery of about 81% and yield of about 29.2%.
A still further aspect of the present invention is directed to said process wherein the chemical composition of the solid residue obtained after filtration process comprising
Constituents Na2O MgO Al2O3 SiO2 SO3 Cl K2O CaO P2O5 TiO2 Fe ZnO PbO C
% 0.8 0.9 3.5 6.6 1.6 0.2 1.0 6.3 0.1 0.2 45.9 2.2 0.3 3.6
A still further aspect of the present invention is directed to said process whereinNa2O content could be reduced by 40-44%, K2O content could be reduced by 70-74%, with significant increase in the Fe content of 40-50% in the solid residue with simultaneous reduction in the sulfur and chlorine content by 46-50% and 80-85% respectively.
The above and other aspects and advantages of the present invention are described hereunder in greater details with reference to the following accompanying illustrative drawing and example.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWING
Fig. 1:shows the process flowsheet to recover carbon and remove alkali from the blast furnace pot dust according to present invention.
DETAILED DESCRIPTION OF THE INVENTION WITH REFERENCE TO ACCOMPANYING DRAWING
The present invention is directed to provide a processing route for comprehensive recycling of pot dust by recovering carbon and removing alkali from it. In order to achieve the above object, the process flow adopted in the present invention is as follows:
Step 1: Froth flotation of pot dust to separate the carbon bearing particles.
• The dry pot dust is subjected to the flotation cell with water maintaining a pulp density of 30-40%.
• Diesel oil with the dosage of 200-300 g/ton are used as collector and conditioned for 5 min.
• Methyl isobutyl carbinol (MIBC) with dosage of 50-100 g/ton is used as frother and conditioned for 2 min.
• The froth is filtered and dried to obtain a high purity carbon rich product.
Step 2: Leaching of pot dust with water
• The dry pot dust is subjected to the leaching tank with water maintaining a pulp density of 30-40%.
• The solution is agitated with the help of a mechanical stirrer for 30-45 min.
• The temperature of the pulp is kept at >900C
Step3: Filtration
• The solution present in the leaching tank is filtered using a filter press
• The solid residue is dried and reused in iron making
Step4: Crystallization and extraction of salts from the leach liquor
• Heating the leach liquor gently to allow the water to evaporate.
• As the water evaporate, the concentration of salt in the solution increases
• Gradually the crystals of various salts start to precipitate.
• Filter the precipitate to obtain the solid residue containing different salts (Na2SO4, K2SO4, KCl, NaCl).
Step 5: Condensation of evaporated water for reuse
• Condensation of evaporated water and reuse it in theleaching process.
Accompanying Fig. 1 illustrates the proposed flowsheet for carbon recover and alkali removal process according to present invention.
As can be observed from Fig. 1, the present invention uses pot dust from the blast furnace pot dust to remove the alkali, which could be useful for the sinter/ pellet/ briquette making application. Initially, the feed material is mixed with water to prepare a pulp of 30-40% solid concentration and subjected to a flotation cell. The impeller speed is kept at 1500rpm to ensure the proper mixing of water with the solid particles. In this process, diesel oil serves as the collector, while MIBC functions as the frother. Diesel oil is used at a dosage ranging between 200-300 g/ton, and MIBC at a dosage ranging between 50-100 g/ton. Following a 5-minute conditioning with diesel oil and a 2-minute conditioning with MIBC, the air valve is opened, allowing air bubbles to adhere to hydrophobic carbon particles. The resulting froth is then filtered and dried to achieve a carbon product of high purity.
The pulp containing the non-froth product is subsequently subjected to a leaching tank for the dissolution of alkali content. The pulp is agitated with the help of a mechanical agitator to ensure proper mixing of water with the solid particles. The leaching time and temperature are ranged between 30 to 45 minutes and 90-950C respectively. Later the leached solution is carefully filtered and the leach residue is allowed to cool down. The obtained solid residue would be dealkalized, which could be recirculated through the sinter/ pellet/ briquette plant.
The leach solution carrying various dissolved salts is heated gradually, leading to evaporation of water. With increasing concentration of salts during evaporation, salt precipitation occurs within the solution. These precipitates can be extracted from the solution through filtration or any other mechanism. The filter residue is then air-dried or subjected to hot air for drying. Later, the evaporated water could be condensed and reused in the filtration process.
Example of the Best Workable Embodiment of the Invention
Table 1 shows the chemical composition of the pot dust used for the present investigation. As can be observed, the feed material is containing about 5% of alkali (Na2O+K2O), while the SO3content is about 3.2%. In addition, it is also containing 30.9% of Fe and 26.9% of carbon.

Table 1. Elemental composition of pot dust (XRF analysis)
Constituents Na2O MgO Al2O3 SiO2 SO3 Cl K2O CaO P2O5 TiO2 Fe ZnO PbO C
% 1.5 0.9 3.6 7.0 3.2 1.5 3.5 5.6 0.1 0.2 30.9 1.4 0.1 26.9
By following the process flowsheet illustrated in Fig. 1, initially the feed sample is subjected to the flotation process. The impeller speed is kept constant at 1500 rpm. The optimum dosages of diesel oil and MIBC were obtained at 250 g/ton and 60 g/ton respectively. The obtained froth could be enriched to 83% of total carbon content with an overall recovery of about 81% and yield of about 29.2%. The chemical composition of froth product is presented in Table 2.
Table 2. Chemical composition of froth product
Constituents Na2O MgO Al2O3 SiO2 SO3 Cl K2O CaO P2O5 TiO2 Fe ZnO PbO C
% 0.1 0.1 2.2 8.7 - - 0.5 0.1 - - 3.2 - - 83.7

The non-froth present in the pulp is subjected to the leaching process. The pulp is conditioned by a mechanical agitator for 75 minutes at 70-950C temperature. Then the pulp is filtered using a filter press and the obtained solid residue is less in alkali content. The Na2O content could be reduced by 40-44%, wherein K2O content could be reduced by 70-74%. In addition, there is a significant increase of 40-50% in the Fe content in the solid residue could also be observed. Simultaneously, the sulfur and chlorine content could be reduced by 46-50% and 80-85% respectively. Table 2 shows the chemical composition of the solid residue obtained after filtration process.
Table 2. Chemical composition of solid residue
Constituents Na2O MgO Al2O3 SiO2 SO3 Cl K2O CaO P2O5 TiO2 Fe ZnO PbO C
% 0.8 0.9 3.5 6.6 1.6 0.2 1.0 6.3 0.1 0.2 45.9 2.2 0.3 3.6
Further, the leached liquor containing various dissolved elements, subjected to the evaporation crystallization process by gently heating the solution. With the increase in time the solution becomes saturated and solid crystals get precipitated within the solution. Later, the solution is filtered and the solid crystals are collected by filtering the solution carefully. In addition, the water evaporated during the heating of the solution could be reused in the flotation process. The chemical composition of the precipitate is given in Table 4.
Table 4. Chemical composition of the obtained precipitate.
Constituents Na2O MgO Al2O3 SiO2 SO3 Cl K2O CaO P2O5 TiO2 Fe ZnO PbO C
% 5.7 0.04 0.4 15.0 16.1 52.2 0.1 1.6 2.6
It is thus possible by way of the present invention to provide a simple, fast and cost effective process for comprehensive recycling of blast furnace pot dust by recovering carbon and eliminating the deteriorating elements like alkali, involving froth floatation, water leaching, filtration, evaporation of filtrate and condensation of evaporated water to reuse in the flotation process, and thereby making solid residue of filtration of leaching solution suitable to be treated as a raw material in sinter/pellet/briquette plant and obtain alkali salts as separate product by evaporation/crystallization for various industrial application.
, Claims:We Claim:

1. A process for the recovery of carbon and removal of alkali from the blast furnace flue/pot dust for rendering it suitable for recirculating in steel plant operations including as input in sinter/ pellet/ briquette plant comprising
the steps of
(i) Step 1: separating the carbon bearing particles and thereby recovering carbon by Froth flotation of pot dust comprising
(a)Subjecting the dry pot dust to the flotation cell with water maintaining a pulp density of 30-40%;
(b)Dosing Diesel oil with the dosage of 200-300 g/ton as collector;
(c)Dosing Methyl isobutyl carbinol (MIBC) with dosage of 50-100 g/ton as frother;
(d)filtering and drying the floated froth to thus recover a high purity carbon rich product;
(ii) Step 2: removal of alkali from the non-froth portion of pot dust pulp obtained in step 1 by leaching with water for the dissolution of alkali content and subjecting to filtration thereby producing solid residue substantially free of alkali content which is suitable for reuse in iron making such as in sinter/pellet/briquette making plant.

2. The process as claimed in claim 1 comprising the step of processing the leach liquor from said step of alkali removal for recovery of valuable solid residue rich in different salts including selectively Na2SO4, K2SO4, KCl, NaCl following :
I) subjecting the leach liquor to Crystallization and extraction of salts therefrom by evaporation comprising
(a)Heating the leach liquor gently to allow the water to evaporate, to thereby increase the concentration of salt in the solution ;
(b)Allowing the crystals of various salts to precipitate gradually;
(c)Filtering the precipitate to separate the solid residue containing different salts (Na2SO4, K2SO4, KCl, NaCl) for use as separatemarketable byproduct for the variety of application including but not limited to the fertilizer, cement, chemical reagents manufacturing etc.
II) Condensation of evaporated water for reusing it as make up water in the floatation or leaching process.

3. The process for the recovery of carbon and removal of alkali from the blast furnace flue/pot dust as claimed in anyone of claims 1 or 2 for recirculating the residue product in steel plant operations including as input in sinter/ pellet/ briquette plant comprising
physio-chemical and hydrometallurgical processing for separation of carbon and alkali involving the steps of

(i) Step 1: separating the carbon bearing particles by Froth flotation of pot dust comprising
(a)Subjecting the dry pot dust to the flotation cell with water maintaining a pulp density of 30-40% and maintaining impeller speed constant at 1500 rpm;
(b)Dosing Diesel oil with the dosage of 200-300 g/ton as collector and conditioning for 5 min;
(c)Dosing Methyl isobutyl carbinol (MIBC) with dosage of 50-100 g/ton as frother and conditioning for 2 min;
(d) filtering and drying the floated froth to obtain a high purity carbon rich product;
(ii) Step 2: Leaching of non-froth portion of pot dust pulp obtained in step 1 with water for the dissolution of alkali content comprising
(a)subjecting the dry pot dust to leaching in the leaching tank with water maintaining a pulp density of 30-40%;
(b)agitataing the solution with the help of a mechanical stirrer for 30-45 min maintaining temperature of the pulp at 80-950C preferably 900C; and
(c) subjecting the leached solution to filtration.
(iii) Step3: Filtration comprising
(a) filtering the solution present in the leaching tank using a filter press;
(b)The solid residue obtained having low alkali content is dried, making it suitable for reuse in iron making such as in sinter/pellet/briquette making plant.
(iv) Step 4: subjecting the leach liquor to Crystallization and extraction of salts therefrom by evaporation comprising
(a)Heating the leach liquor gently to allow the water to evaporate, to thereby increase the concentration of salt in the solution;
(b)Allowing the crystals of various salts to precipitate gradually;
(c)Filtering the precipitate to separate the solid residue containing different salts (Na2SO4, K2SO4, KCl, NaCl) for use as separate marketable byproduct for the variety of application including but not limited to the fertilizer, cement, chemical reagents manufacturing etc.
(v) Step 5: Condensation of evaporated water for reusing it as make up water in the floatation or leaching process.
4. The process as claimed in anyone of claims 1 to 3 wherein said leaching step comprising water leaching of pot dust at a temperature of 80-950C for 60minutes.
5. The process as claimed in anyone of claims 1 to 4 wherein the filtrate obtained in said filtration step is evaporated gently leading to super-saturation of the solution whereby the gradual increase in concentration over time initiates the crystallization and precipitation process.
6. The process as claimed in anyone of claims 1 to 5 wherein the solid residue obtained after filtering the leached solution has lower sulfur content suitable for use in sinter plant.
7. The process as claimed in anyone of claims 1 to 6 wherein the filter residue is air-dried or subjected to hot air for drying.
8. The process as claimed in anyone of claims 1 to 7 wherein the elemental composition of pot dust used as raw material input comprises
Constituents Na2O MgO Al2O3 SiO2 SO3 Cl K2O CaO P2O5 TiO2 Fe ZnO PbO C
% 1.5 0.9 3.6 7.0 3.2 1.5 3.5 5.6 0.1 0.2 30.9 1.4 0.1 26.9

9. The process as claimed in anyone of claims 1 to 8 wherein froth is enriched to 83% of total carbon content with an overall recovery of about 81% and yield of about 29.2%.
10. The process as claimed in anyone of claims 1 to 9 wherein the chemical composition of the solid residue obtained after filtration process comprising
Constituents Na2O MgO Al2O3 SiO2 SO3 Cl K2O CaO P2O5 TiO2 Fe ZnO PbO C
% 0.8 0.9 3.5 6.6 1.6 0.2 1.0 6.3 0.1 0.2 45.9 2.2 0.3 3.6
11. The process as claimed in anyone of claims 1 to 10 wherein Na2O content could be reduced by 40-44%, K2O content could be reduced by 70-74%, with significant increase in the Fe content of 40-50% in the solid residue with simultaneous reduction in the sulfur and chlorine content by 46-50% and 80-85% respectively.

Dated this the 4th day of November, 2023
Anjan Sen
Of Anjan Sen & Associates
(Applicant’s Agent)
IN/PA-199