Title of Invention

"DEVELOPMENT OF A NOVEL PROCESS FOR THE CONVERSION OF WASTE COMPOSITE PROPELLANT INTO LIQUID FERTILIZER"

Abstract

In accordance with the invention, a novel method is described to convert waste composite propellant into liquid fertilizer and analysis comprising, digesting of waste composite propellant with dilute nitric acid to achieve a homogeneous solution after reflux. The obtained solution was further treated with excess of an alkali solution to remove aluminium as Al(OH)3. The obtained liquid was further neutralized with orthophosphoric acid and fully analyzed. The process is cost-effective and environment friendly.

Full Text

FIELD OF INVENTION The present invention relates to a novel process for the conversion of waste composite propeUant into a liquid fertilizer with desired content of nitrogen, phosphorous and potassium using chemical method. More particularly, this invention relates to removal of aluminium content as it is detrimental to soil. The invention relates to a process to convert waste propeUant into perchiorate free liquid fertilizer. BACKGROUND OF ART: Composite propeUant basically contains an oxidizer such as ammonium perchiorate, a metallic fuel such as aluminium powder and a binder mainly hydroxyl terminated polybutadiene. A considerable amount of waste propeUant is produced during the manufacture of solid rocket motor. Such waste propeUant is caused by number of factors including, for example, the excess cast into motor casing to compensate for shrinkage, from master batches that do not meet specifications and expiry of life of motors that are removed from service. Much of this waste propeUant has been scraped in the past and burned in open burning pits since the flammability and rubbery characteristics have been believed to prevent economical reclamation. However, the cost of burning waste propeUant is considerable. In addition, open pit burning is hazardous and environmentally unacceptable. Due to Environmental Protection Agency (EPA) restrictions limiting open burning of hazardous waste and munitions, NASA as well as other military organizations world wide have adopted new regulation to protect environment form conventional means of destructions of propeUant such as launch-to-destroy static firing or open burning. The most widely used alternative to current open burning methods involve the use of incineration, molten salt oxidation, supercritical waste oxidation, hydrothermal oxidation, biodegradation and chemical treatment processes. However, these processes are either costly or not get exploited to large operations. Therefore, the objective of the present invention is to develop a novel process for converting waste composite propellant into liquid fertilizer as cost-effective and environmental friendly method. Several methods have been reported in the open literature to convert waste propellant into fertilizer. One of the patented method claims to have developed a single base propellant (Nitrocellulose based) into liquid fertilizer as "ACTOSOL", by alkaline hydrolysis. The conversion of waste composite propellant into liquid fertilizer has not been revealed in literature. However, the method for extracting ammonium perchlorate from cottiposite propellant using anhydrous liquid ammonia at high pressure is patented. Another method claims to have developed to recover aluminium powder from composite propellant using sodium methoxide and cross-esterified alcohols. Still another method claims to have developed a process to convert composite propellant into C02, H20, N20 and other products by subjecting of compressed air in super critical steam under several atmospheric pressures. The treatment of propellant with a base is well known in art for nitrate esters containing propellant compositions such as single base, double base and triple base propellants and not for composite propellant based in HTPB, ammonium perchlorate and aluminium powder. Moreover, the main emphasis of above methods are separating a constituent of composite propellant into powder form or converting it into gaseous products and not into liquid fertilizer. OBJECT OF THE INVENTION: The main object of die present invention is to develop a novel process for conversion of waste composite propellant into liquid fertilizer by chemical treatment to have desired content of NPK with negligible quantity of aluminium powder, as it is detrimental to soil. Specifically, the present invention is based upon the development of a novel process to convert composite propellant into liquid fertilizer as the cost-effective and environmental friendly method. Another object of the present invention is to provide a novel process for conversion of waste composite propellant into liquid fertilizer by chemical treatment to have desired content of NPK with negligible quantity of aluminium powder, as it is detrimental to soil. Still another objective of the present invention is to provide a process to convert composite propellant into liquid fertilizer with negligible quantity of perchlorate. SUMMARY OF INVENTION: The present invention proposes a novel method to convert waste composite propellant into liquid fertilizer by chemical treatment. The process is cost-effective and environmental friendly. The obtained liquid fertilizer has been evaluated for the desired quantity of N03", P043"* K and Al content using Ion chromatograph and Inductively Coupled Plasma Atomic Emission Spectrometry (ICP-IMES). In accordance with the invention, a novel method is described to convert waste composite propellant into liquid fertilizer and analysis comprising, digesting of waste composite propellant with dilute nitric acid to achieve a homogeneous solution after reflux. The obtained solution was further treated with excess of an alkali solution to remove aluminium as Al(OH)3. The obtained liquid was further neutralized with orthophosphoric acid and fully analyzed. STATEMENT OF INVENTION: According to the present invention there is provided a novel process for the conversion of waste composite propellant into liquid fertilizer comprising: (a) Adding pieces of cured waste composite propellant to nitric acid; (b) refluxing of solution obtained in step (a) to achieve homogeneous solution; (c) cooling of the homogeneous solution obtained in step (b); (d) adding KOH to the solution obtained in step (c) alongwith continuous stirring; (e) separating precipitate of Al (OH)3 and Filtrate by filtration of the solution obtained in step (d); (f) adding orthophosphoric acid to the filtrate obtained in step (e) maintaining pH between 7-8 to obtain the liquid fertilizer. DESCRIPTION OF THE PROCESS The present invention is useful for composite propellant comprising HTPB, aluminium powder and ammonium perchlorate, optionally comprising process aids and curatives. According to present invention, the process details to convert waste composite propellant into liquid fertilizer and analysis comprise following steps: (a) Adding pieces of cured waste composite propellant to nitric acid; (b) refluxing of solution obtained in step (a) to achieve homogeneous solution; (c) cooling of the homogeneous solution obtained in step (b); (d) adding KOH to the solution obtained in step (c) alongwith continuous stirring; (e) separating precipitate of Al (OH)3 and filtrate by filtration of the solution obtained in step (d); (f) adding orthophosphoric acid to the filtrate obtained in step (e) maintaining pH between 7-8 to obtain the liquid fertilizer. The cured pieces of waste composite propellant are digested in nitric acid. All the steps carried out during digestion and neutralization are in aqueous medium. Therefore, the question of exothermicity does not arise in the present invention as organic solvents are not used, as in prior art processes. The propellant can be cured before adding to nitric acid. Curing is hardening i.e., reaction of hydroxyl group of HTPB with NCO group of curative to form urethane linkage (RNHCOO-) at 45-50 degree C for a period of 5 to 7 days in water jacketed oven. However, the curing cycle depends on mass/web of the propellant grain and temperature of curing. The present invention is suitable for cured composite propellants irrespective of adopted cured cycle. The pieces of cured waste composite propellant can be cut into pieces by hand saw at RH 55 ± 10%. The size of cut pieces of waste composite propellant is in the range of 5mm to 10mm. The addition of cured pieces of composite in step (a) can be done portion wise. The amount of portion of addition of waste composite propellant into nitric acid can be 2-3 gram of composite per installment. For digestion, the amount of nitric acid is 8 to 10 ml per gram of composite propellant. The nitric acid has a concentration in the range of 35 to 100%. The solution in step (c) is cooled upto room temperature i.e. from 20 degree C to 40 degree C. KOH is used in step (d) for the precipitation of aluminium hydroxide. The range of concentration of KOH used for the present invention is 3-7 M KOH and the ratio of solution obtained in step (c) to KOH added is 1:0.8 to 1:1.5. KOH can be added drop wise over a period of 20-40 minutes, preferably 30 minutes. The aluminium hydroxide precipitate obtained in step (d) is washed by plenty of water. The aluminium hydroxide is dried in the temperature range of 105 to 110 degree C in air oven for 2-3 hours. Estimation of aluminium content after precipitation can be done by ICP-AES. The percentage of aluminium in Al(OH)3 estimated is 34.3-34.5%. In step (e), for neutralization, the requirement of orthophosphoric aicd for the present invention is in the range of 3-5 ml, hence, drop-wise addition of orthophosphoric acid is carried out. In step (f) the pH is maintained in the range of 7-8. The period of addition for orthophosphoric acid is 10-15 minutes. The solution, obtained was analyzed for N03", CKV, NH4+ using Ion chromatography and K is estimated by ICP-AES. The process of the present invention can be easily automated. The novel process of the present invention for conversion of waste composite propellant into liquid fertilizer by chemical treatment to have desired content of NPK with negligible quantity of aluminium powder, as it is detrimental to soil is cost-effective and environmental friendly. The novel process for conversion of waste composite propellant into liquid fertilizer by chemical treatment provides desired content of NPK with negligible quantity of aluminium powder, as it is detrimental to soil and also remove aluminium content from composite propellant. The liquid fertilizer obtained from process of present invention has negligible quantity of perchlorate. Working Example: Example 1: To a 1 Lround bottom flask equipped with mechanical stirrer and addition funnel, about 80 ml of 50% nitric acid is carefully transferred. About 10 g of waste composite propellant, cut into small pieces, was added portion wise to the above solution under stirring. It was kept over water bath and refluxed for 4- 5 hrs to achieve homogeneous solution. The noxious gaseous products produced during reflux were passed through alkaline solution to avoid environmental pollution. The homogeneous solution was treated with drop-wise addition of 5M KOH solution (110 ml) with stirring. The white precipitate obtained was filtered through suction and washed with plenty of water. The precipitate was dried in air oven in the temperature range of 105 to 110 degree C for 2-3 hrs. Al(OH)3 thus obtained was analyzed using Inductively Coupled Plasma-Atomic Emission Spectrometry (ICP-AES). The analyzed percentage of aluminium in Al(OH)3 was found to be 34.3-34.5 (theoretical percentage of aluminium in Al(OH)3 is around 34.6. The alkaline filtrate was neutralized by drop wise addition of orthophosphotic acid under stirring. The solution, obtained was analyzed for N03 C1O4 NH4+ using Ion chromatography and K is estimated by ICP-AES. Example 2: The results obtained after analyzing for NO3", C1O4 NH4+ using Ion chromatography and K estimated by ICP-AES are as follows: NO3" - 10-11%,, 0.03-0.04% and 4.0-4.5 %, PO43" - 3-4% C1O4 - 0.03-0.04% NH4+ - 4.0-4.5%, K - 9-11% We claim: 1. A novel process for the conversion of waste composite propellant into liquid fertilizer comprising: (a) Adding pieces of cured waste composite propellant to nitric acid; (b) refluxing of solution obtained in step (a) to achieve homogeneous solution; (c) cooling of the homogeneous solution obtained in step (b); (d) adding KOH to the solution obtained in step (c) alongwith continuous stirring; (e) separating precipitate of Al (OH)3 and filtrate by filtration of the solution obtained in step (d); (f) adding orthophosphoric acid to the filtrate obtained in step (e) maintaining pH between 7-8 to obtain the liquid fertilizer. 2. The process as claimed in claim 1, wherein the composite propellant is a propellant comprising HTPB, aluminium powder and ammonium perchlorate. 3. The process as claimed in claim 1, wherein the cured waste composite propellant is obtained by reaction of hydroxyl group of HTPB with NCO group of curative at 45-50 degree C for a period of 5 to 7 days in water jacketed oven. 4. The process as claimed in claim 1, wherein the pieces of cured waste composite propellant are obtained by cutting by hand saw at RH 55 ± 10%. 5. The process as claimed in claim 1 or 3, wherein the size of pieces of waste composite propellant is in the range of 5mm to 10mm. 6. The process as claimed in claim 1, wherein in step (c) the homogeneous solution is cooled to a temperature of 20 degree to 40 degree C. 7. The process as claimed in claim 1 wherein, the amount of nitric acid is 8 to 10 ml per gram of composite propellant. 8. The process as claimed in claim 1, wherein the nitric acid has a concentration of 35 to 100%. 9. The process as claimed in claim 1, wherein in step (d), KOH has a concentration of 3-7 M. 10. The process as claimed in claim 1, wherein in step (d) the ratio of solution obtained in step (c) to KOH is 1:0.8 to 1:1.5. 11. The process as claimed in claim 1, wherein the orthophosphoric acid is used as neutralizing medium. 12. The process as claimed in claim 1, wherein the concentration of NO3", PO43" , C1O4", NH4+and K in the fertilizer is in the range of 10-11%, 3-4 %, 0.03-0.04% and 4.0-4.5 % and 9-11 % respectively. 13. The process for the conversion of waste composite propellant into fertilizer such as herein described with reference to the foregoing examples.

Documents:

1168-del-2009-Abstract-(01-08-2014).pdf

1168-del-2009-abstract.pdf

1168-del-2009-Claims-(01-08-2014).pdf

1168-del-2009-claims.pdf

1168-del-2009-Correspondence Others-(01-08-2014).pdf

1168-DEL-2009-Correspondence-Others (23-10-2009).pdf

1168-del-2009-correspondence-others.pdf

1168-del-2009-description (conmplete).pdf

1168-del-2009-form-1.pdf

1168-DEL-2009-Form-18.pdf

1168-del-2009-form-2.pdf

1168-del-2009-form-3.pdf

1168-del-2009-form-5.pdf

1168-DEL-2009-GPA (23-10-2009).pdf