Description:FIELD OF THE INVENTION
The present invention relates to a novel composition for recovery of Platinum group metals such as Platinum, Rhodium and Palladium from the instruments used in manufacturing of chemicals such as Nitric Acid and Caprolactam. More specifically, the present invention provides a non-acidic and mild liquid composition for removal of deposited Platinum group metals on the reaction instruments. The present invention also provides a simple and non-acidic process for recovery of Platinum group metals from the internal walls of the instruments.

BACKGROUND OF INVENTION:
The Platinum Group Metals (PGMs) includes ruthenium (Ru), rhodium (Rh), palladium (Pd), osmium (Os), iridium (Ir), and platinum (Pt). The major applications of PGMs are as catalysts in automotive industry, petroleum refining, environmental (gas remediation), industrial chemical production (e.g., Ammonia production, industrial fine chemicals like Nitric acid, Caprolactam), electronics, and medical fields. The varied applications of PGMs are of considerable importance in the modern era, so an understanding of ongoing PGM demand and its end-uses as well as recovery is critical for managing PGM reserves.
Most notably, PGMs find widespread usage in a variety of catalytic processes, such as the production of Ammonium Nitrate, Nitric Acid and Caprolactam. Wherein the manufacturing process of Nitric Acid or Caprolactam begins with the oxidation of Ammonia to Nitric Oxides (NOx) by the Ostwald process. This reaction takes place at high temperature and medium to high pressure and is catalyzed by Platinum group metals (PGMs) such as Platinum, Rhodium and Palladium.
During the course of production, small quantities of Platinum, Rhodium and Palladium get eroded from the gauzes. The higher the operating pressure and temperature, the greater the loss of these metals. Therefore, recovery systems are installed, such as mechanical filters and recovery or catchment gauzes.
However, in spite of these measures, significant quantities of Pt, Rh and Pd escape and accumulate in the production heat train of equipment (vertical or horizontal expander gas heater, waste heat boiler, tail gas heater, shell and tube heat exchangers, right up to the storage tanks). Since the quantities become significant over a period of time (2-3 years and more), physical and chemical methods have been developed in order to recover the PGMs, for example, mechanical cleaning, hydro-jet blasting and treatment with mineral acids. Since PGMs are precious metals, their dissolution requires strong oxidizing agents such as chlorine gas and aqua regia (mixture of concentrated Nitric and Hydrochloric acids).
The chemical methods give highest recoveries over the physical methods. The standard chemical method involves the use of mineral acids, such as phosphoric acid, at high temperature for loosening the deposited PGMs from the surfaces and subsequent recovery.
Companies which are known to carry out recovery of PGMs by such methods include Arvos, Metallix Refining and RS Bruce. The methods based on the use of chemicals suffer from drawbacks such as attacking the material of construction of the equipment, fume generation due to very acidic solution, low recovery of the PGMs when the material of construction is not attacked, etc. These acids also pose serious occupational hazards and danger to the instruments in use.
Hence, there is an urgent need to develop a liquid composition which is mild in nature, which can extract the metals efficiently at ambient temperature, which does not generate any fumes, which is water-based and which does not pose any risk either to equipment or operators nor pose any other occupational safety hazards. Also, there is also need in the art for an easy process for effective leaching of deposited PGMs from the internal walls of instruments without destroying the instrument application.
The inventors have done extensive testing to overcome the problems in recovery of PGMs by providing a non-acidic composition of alkali salt having mild pH, wherein the said alkali salt is prepared by reacting a strong base and weak acid. It has been found in the present invention that the incomplete neutralisation of strong base with weak acid and maintaining the pH using buffering agent between pH 5 to 6 can significantly improve the removal of deposited PGMs on internal walls of manufacturing instruments even at ambient temperature. At the same time, said composition need not required complex processing steps. The process includes only contacting the instrument surface with said composition for time between 5 min to 24 h or more.
Surprisingly, the PGMs are recovered in large quantities using present invention composition and process as compare to recoveries with strong acids used in prior arts. Therefore, the present novel composition provided in present invention is very effective, eco-friendly and safe.

OBJECTIVES OF THE INVENTION
The main objective of the present invention is to provide a safe, non-acidic and effective composition for recovery of Platinum, Rhodium and Palladium metals deposited on manufacturing instruments.
Consequently, another object of the present invention is to provide a simple method for recovery of Platinum, Rhodium and Palladium metals deposited on manufacturing instruments.
Another objective of the present invention is to provide the effective liquid composition which can be used onsite inline manufacturing plant without dismantling it for cleaning.
One more objective of the present invention is to provide the mild liquid composition that shows recovery of PGMs at room temperature between 20 to 40 Deg C.
Further, objective of the present invention is to provide a process of recovery of PGMs that does not require use of strong mineral acids or separate effluent treatment process because the composition is non-hazardous and can be treated easily with existing manufacturing plant effluent methods.

SUMMARY OF INVENTION:
The present invention provides a non-acidic composition for recovery of deposited platinum group metals from the instruments used in manufacturing of chemicals such as Nitric Acid and Caprolactam chemicals and any other chemicals starting with oxidation of ammonia to NOx. Further, the material of construction of instruments selected from mild steel, stainless steel 300 series, stainless steel 400 series and high nickel alloys such as Incoloy.
Wherein the instruments selected from scrap metal instruments, dismantled instruments and in-line installed instruments.
More preferably, the present invention provides a non-acidic composition for recovery of deposited platinum group metals comprising of; alkali salt prepared by reacting a weak acid in 0.1 to 2.5 Mol/Lit concentration and strong alkali in 0.1 to 4.0 Mol/Lit concentration, characterized in that the pH of said alkali salt is between pH 5 to 6 using buffering agent.
Wherein weak acid selected from Phosphonic acid; 1-Hydroxyethylidene-1,1-diphosphonic acid (Etidronic acid); Diethylenetriamine penta(methylene phosphonic acid); 2-Phosphonobutane-1,2,4-tricarboxylic acid; Amino(trimethylene phosphonic acid) and combinations thereof and strong alkali selected from Sodium hydroxide, potassium hydroxide and combination thereof.
The buffering agent selected from Acetates; Citrates; Phosphates; Oxalates; 2-[4-(2-hydroxyethyl)piperazin-1-yl]ethanesulfonic acid; (3-(N-morpholino)propanesulfonic acid); tris(hydroxymethyl)aminomethane (TRIS); Borates; Hydrogen phthalates; Dihydrogen orthophosphates; Alkali tartarates and combinations thereof.
The present invention also provides a process for recovery of deposited platinum group metals from the instruments used in manufacturing of chemicals such as Nitric Acid and Caprolactam chemicals using non-acidic composition, said process comprising the following steps:
i. contacting said instruments used in manufacturing of chemicals with an alkali salt solution having pH between 5 to 6 for time between 5 minutes to 72 Hrs, wherein alkali salt solution is selected from the composition comprising weak acid in 0.1 to 2.5 Mol/Lit concentration and Strong alkali in 0.1 to 4.0 Mol/Lit concentration.
ii. Maintaining the temperature of solution at room temperature and, optionally, increasing the temperature of said solution from 20 to 60 Deg C to leach platinum group metals from instruments into alkali salt solution to obtained a alkali salt mixture, preferably the temperature selected between 20 to 40 Deg C.
iii. Separating alkali salt mixture from instrument and
iv. Recovering the dissolved platinum group metals from said alkali salt mixture using known suitable separation techniques.

The weak acid selected from Phosphonic acid; 1-Hydroxyethylidene-1,1-diphosphonic acid (Etidronic acid); Diethylenetriamine penta(methylene phosphonic acid); 2-Phosphonobutane-1,2,4-tricarboxylic acid; Amino(trimethylene phosphonic acid) and combinations thereof and strong alkali selected from Sodium hydroxide, potassium hydroxide and combination thereof.
The buffering agent is selected from Acetates; Citrates; Phosphates; Oxalates; 2-[4-(2-hydroxyethyl)piperazin-1-yl]ethanesulfonic acid; (3-(N-morpholino)propanesulfonic acid); tris(hydroxymethyl)aminomethane (TRIS); Borates; Hydrogen phthalates; Dihydrogen orthophosphates; Alkali tartarates and combinations thereof.

DETAILED DESCRIPTION OF THE INVENTION:
In one aspect, embodiments disclosed herein relate to a highly efficient concept to extract deposited PGMs from manufacturing instruments using alkali salts. While this particular Alkali salt is non-acidic, which is eliminating the need for strong hazardous chemicals and separate processes to achieve effluent treatment.
The present invention provides a mild and effective composition for recovery of catalyst-based Palladium group metals (PGMs) deposited on internal walls or surfaces of manufacturing instruments such as used in manufacturing of nitric acid and caprolactam, such as but not restricted to vertical and horizontal Expander Gas Heater, Waste Heat Boiler, Tail Gas Heater, Elbows and Cooler Condensers. This composition can easily be carried on-site on running equipment or off-site on scrapped equipment.
Therefore, the objective of overcoming prior arts problems is achieved by developing a non-acidic solution having pH between 5 to 6. Further, the said composition is effective to remove the deposited metals on internal walls of instrument within 1 h to 24 h at temperature between 20 to 60 deg C.
The present invention also describes a simple process of recovery of PGMs from plants manufacturing nitric acid and caprolactam, by the use of mild chemicals and reagents at near neutral pH value.
The process is relatively quick and does not release any fumes during the process. It is carried out at ambient temperature of 20-45 deg C.
In accordance with the present invention, the composition is comprising of mixture of weak acid and its derivatives, alkali and buffering agent to adjust the pH between 5 to 6.
In an important embodiment of the present invention, the present invention provides a non-acid composition for recovery of PGMs comprising of an alkali salt prepared by reaction of Weak acid in 0.1 to 2.5 Mol/Lit concentration and Strong alkali in 0.1 to 4.0 Mol/Lit concentration and pH being adjusted to between 5 to 6 and using suitable buffering agent.
Wherein the weak acid is selected from Phosphonic acid and its derivatives. The non limiting examples of derivatives of Phosphonic acid include 1-Hydroxyethylidene-1,1-diphosphonic acid (Etidronic acid), Diethylenetriamine penta(methylene phosphonic acid), 2-Phosphonobutane-1,2,4-tricarboxylic acid and Amino(trimethylene phosphonic acid).
Wherein the alkali is selected from Sodium hydroxide and Potassium hydroxide or combination thereof.
Wherein the non-limiting examples of buffering agent include Acetates, Citrates, Phosphates, Oxalates, Borates, Hydrogen phthalates, Dihydrogen orthophosphates, Alkali tartarates as well as Soft Buffers such as HEPES and TRIS and their salts.
In second embodiment of the present invention, the invention provides a simple process for leaching and recovering PGMs from manufacturing metal instruments not limiting to mild steel or stainless steel, the process comprising the steps of:
Step 1) contacting manufacturing instrument part (scrapped or installed) comprising deposited PGMs with a alkali salt having pH between 5 to 6, wherein the alkali salt comprises a weak acid and an alkali and optionally a buffering agent;.
Step 2) leaching the PGMs from the basic material of construction of instrument and extracting the PGMs into the said alkali salt solution with or without heat; wherein the alkali salt solution temperature can be raised between 20 to 60 deg C, or more preferably between 30 to 45 deg C; wherein the step of leaching and extracting is conducted for time ranging between 5 minutes to 72 h, more preferably from 1 h to 24 h,
Step 3) recovering the dissolved PGMs residues from the alkali solution by known and simple suitable separation techniques such as filtration, centrifugation and drying.
Wherein, the loosening of the PGMs deposits from material construction is due to possible reduction in surface tension, complexing of the displaced iron from steel substrate and thereby favouring the loosing of the PGM particles, PGMs being heavy, they drop down to the bottom of the solution after being loosened.
The present invention is further described with the help of the following examples, which are given by way of illustration and therefore should not be construed to limit the scope of the Invention as claimed in any manner.

Example 1: Effect of Different Acids
Sample and method Used: Samples were prepared from scrapped Nitric Acid Plant Equipment procured from a local Nitric Acid manufacturer, such as Waste Heat Boiler, by cutting the heat exchanger tubes (1” diameter) to appropriate length (1” to 3”) and weighing the cut samples before (initial) and after the completion of the recovery process. Residues which had fallen to the bottom of the bath or had loosened were collected by filtration, dried and weighed. Typically, a cut tube of 1” diameter and 2” length was suspended in 500 mL of the bath at the specified temperature (room temperature, 50 deg C, 60 deg C) and for the specified length of time, without any agitation.
Experimental conditions: Temperature and time mentioned in Table.
Average tube area: 27.500 sq. in.
Material: Mild steel or stainless steel coated with PGMs.
Base used: Nil
Test no. acid Wt. loss of PGMs
mg/sq.in. at RT/4h Wt. loss of PGMs
mg/sq.in. at 50deg C/4h Observation
1 1-Hydroxyethylidene-1,1-diphosphonic acid 5.8 18.0 Substrate not attacked, pH stable
2 1% w/v phosphoric acid 44.0 abandoned due to severe gassing of H2 Active, attacks substrate slowly
3 1% w/v hydrochloric acid 10.1 57.2 Active, attacks substrate immediately (vigorous evolution of H2 observed)
4 oxalic acid - - Not active
5 Citric acid - - Not active
6 various phosphonic acids, namely,
1-Hydroxyethylidene-1,1-diphosphonic acid (Etidronic acid), Diethylenetriamine penta(methylene phosphonic acid), 2-Phosphonobutane-1,2,4-tricarboxylic acid and Amino(trimethylene phosphonic acid).
- - Active in removing PGMs, do not attack substrate
Table No. 1
As summarized above in Table 1, the tests were carried out using different acids such as phosphoric acid, hydrochloric acid, oxalic acid, citric acid and various phosphonic acids. Hydrochloric acid was extremely aggressive on the MOC and was not investigated further. Phosphoric acid causes vigourous gassing and gradually attacks the substrate material of construction, especially when the temperature rises due to the exothermic reaction. Accelerated tests were also carried out at 50/60C for one hour.
It was observed that in some cases, there was formation of fumes when the equipment came in contact with the chemical under study. In certain cases, effervescence was observed. In other cases, salt formation and deposits were observed. In other cases, mist formation was observed. Apart from mild effervescence, all other observations were considered as drawbacks for the non-acidic cleaning process. Based on these criteria, only the phosphonic acids and their derivatives were found to be potentially suitable for the purpose. The experiments were carried out on as is product and by adjusting the pH with KOH or NaOH to around 5.5.

Example 2: Effect of Alkali and pH on salt formation of Phosphonic Acid
The said experiment was carried out using different alkali agents to prepare alkali salt for the non-acidic formulation (pH above 5).
Acid Used: Phosphonic Acid tried: 1-Hydroxyethylidene-1,1-diphosphonic acid (etidronic acid)
Test no. Alkali Concentration Part/Moles pH Observation
6 NaOH 50% w/V To 5.5 Cake formation
7 NaOH 40% w/V To 5.5 Cake formation
8 NaOH 25% w/V To 5.5 Cake formation
9 NaOH 20% w/V To 5.5 CLEAR SOLUTION
10 KOH 50% w/V To 5.5 Cake formation
11 KOH 40% w/V To 5.5 Cake formation
12 KOH 30% w/V To 5.5 Cake formation
13 KOH 20% w/V To 5.5 CLEAR SOLUTION
Table No. 2
As summarized above in Table No. 2, while preparing the KOH or NaOH salts of the phosphoric acids, it was observed that the concentrated solutions of KOH or NaOH gave rise to formation of snow-white products with poor solubility in water. The products could not be redissolved in water. The salts prepared by neutralization with NaOH of concentrations above 20% w/V (50%, 30% and 25%) crystallize on standing. Moreover, the crystals do not re-dissolve easily. It was discovered that by using concentrations of 20% (w/V) or less of NaOH to adjust the pH of the acid to 5.5, the product form did not crystallize, nor did it freeze at 4C to 8C. This is an important criterion for global transportation by sea.
For the adjustment of pH of the acids, alkalis were used in different concentrations ranging from 5% to 75%. We discovered that best results are obtained when the concentration of the alkali used to adjust the pH is between 10% and 35%. This gives rise to products which did not precipitate on standing and which did not freeze during storage at 4-8 deg C. This is an important criterion for global sea transport and transport during winter months.
In the application test, adjusting pH to 5.5 with either KOH or NaOH gave good weight loss and easy collection of PGMs and uniform appearance on water jet cleaning. Experiments were tried with NaOH in prill form and in flake form, combination of NaOH and KOH as alkali and using KOH as alkali.
Effect of combination of alkalis: Experimental conditions: room temperature, 24h dipping time; average tube area 28.167 sq. in.,
Material: SS 410 coated with PGMs.
Acid Used: 1-Hydroxyethylidene-1,1-diphosphonic acid (HEDP, etidronic acid)
Test no. Formulation Wt. loss of PGMs at RT/4h
In mg/sq.in.
pH before Test pH after Test
14 HEDP+ 5M NaOH 71.511 5.5 5.72
15 HEDP+ 2.5M NaOH and 2.5M KOH 17.511 5.5 5.72
16 HEDP+ 2.5M KOH 64,69 5.5 5.8
17 HEDP+ 5M KOH 64.69 5.7 5.8
18 HEDP+ 5M NaOH Prills 90.81 5.5 5.73
19 HEDP+ 5M NaOH Flakes 96.34 5.5 5.72
TABLE 3
The results are summarized in above table. It is observed that at pH 5.5, the alkali salts of the phosphonic acids also have the effect of a surfactant and loosen the particles adhering to the surface of the exposed parts of the reactor equipment.

Example 3: Effect of buffering agent
It was observed that the addition of a buffering agent helps in improving the performance of the developed formula (bath stability, pH stability). Buffering agents such as citrates, acetates, borates and phosphates as well as so-called soft buffers such as HEPES, TRIS) can be used. It was discovered that the speed and efficiency of the process of loosening the PGM particles from the surface is significantly improved by buffering the solution with a standard buffer such as Acetate, Citrate, Phosphate, Phthalate, Tetraborate, etc. The results of tests with Sodium Acetate and other buffers tried in the formulation are given below in Table.
It was observed that the concentration of the buffering agent had to be optimized in order to reduce the change in pH during the process of liberating the PGMs from the steel substrate. This also has the benefit of less burden during effluent treatment. Moreover, in the absence of a buffering agent, the pH of the bath after the removal of the PGMs turns highly alkaline, necessitating an additional pH-adjustment step during effluent treatment.

• Composition of formulation as per present invention:
• Ingredients Formulation A (per kg of finished formulation) Formulation B (per kg of finished formulation)
“Standard Formula”
Etidronic Acid (HEDP) 60% 100g 100g
Sodium hydroxide 30g 30g
Sodium Acetate NIL 20g
DM Water 870g 850g
TABLE 4
The formulation is prepared in a specified manner.

• Effect of buffering agent on pH of bath to observe change in pH of solution
Material of Constru-ction pH of bath at R.T.
New formula WITHOUT buffering agent (Formu-A) pH of bath at R.T.
New formula WITH buffering agent- Sodium Acetate, 10g/L (Formu-B) pH of bath at R.T.
New formula WITH buffering agent- Sodium Acetate, 20g/L (Formu-B)
Stainless steel
4hr 16hr 4hr 16hr 4hr 16hr
5.5 8.5 5.5 8.17 5.5 6.67
TABLE 5
• Effect of the non-acidic formula having acid, base and buffering agent
Standard formula: Table 4, Standard Formula (Formulation-B)
Experimental conditions: room temperature, 24h; average tube area 25.00 sq. in.
Material substrate used: SS 410

Test No. BUFFERING AGENT Wt. loss of PGMs
In mg/sq.in.
20 N-2-Hydroxyethylpiperazine-N'-ethane- sulfonic acid HEPES 16.65
21 Sodium tetraborate 18.815
22 Sodium tetraborate 19.431
23 Potassium hydrogen phthalate 25.398
24 Tris(hydroxymethyl)aminomethane 36.859
25 Citric Acid 42.977
26 Boric Acid 48.383
27 N-2-Hydroxyethyulpiperazine-N"-ethanesulfonic acid sodium salt HEPES Na 55.491
28 Sodium acetate 62.33
TABLE 6
Example 4: Comparison of Acidic and non-acidic formulation on recovery of PGMs from instrument surfaces:
SAMPLE: Cut tube containing PGMs from Waste Heat Boiler of Nitric Acid Plant, Results are reported as Average of 3 trials;
Material of construction: SS410
Sample were dipped without movement and with movement.
Sample Tube Area in sq. in. NON-ACIDIC Formulation
(Standard formula B) ACIDIC Formulation 10% HCl solution
Wt. loss mg/sq.in.
after 24h Wt. loss mg/sq.in.
after 48h Wt. loss mg/sq.in.
after 24h Wt. loss mg/sq.in.
after 48h
28.67 sq. in. (Without movement) 59.53 2.6 927 1269
26.84 sq. in. (With movement) 48.56 4.4 337 1402
TABLE 7
Observation from above table No. 7:
1: Collected very high amount of weight loss in acidic HCl solution is due to both PGMs and substrate (material of construction) leaching and continue as time increases.
2. Leaching of PGMs (material Weight loss) in non-acidic bath occurs almost completed within 24 hours.
3: Substrate is not attacked in non-acidic bath.
4. Movement of sample does not give significant benefits in recovery of PGMs.

• Laboratory detection of Metals in leaching solution by ICP-OES, performed on residue obtained from sample of 28.67 sq. in. area using non-acidic formulation as per present invention and treated at Room temperature for 48 Hr.
Metal Test Method Unit Results
Iron (Fe) ICP-OES % 0.59
Palladium (Pd) ICP-OES % 2.80
Platinum (Pt) ICP-OES % 8.34
Rhodium (Rh) ICP-OES mg/kg 463.76
TABLE 8
Example 5: Preparation of non-acidic composition for recovery of deposited platinum group metals having different concentrations as per present invention
Experimental conditions: room temperature, ph-5.5, 24h dipping time; average tube area 28.167 sq. in.
Material of construction: SS 410 coated with pgms
Formulations Formulation C Formulation D
Formulation E

Ingredients w/w Molarity w/w Molarity w/w Molarity
Etidronic Acid (HEDP) 60% 100g/Kg 0.2913M 200g/Kg 0.5826M 50g/Kg 0.146M
Sodium hydroxide 30g/Kg 0.75M 60g/Kg 1.5M 15g/Kg 0.375M
SODIUM ACETATE.3H2O 20g/Kg 0.147M 40g/Kg 0.294M 10g/Kg 0.0735M
DM Water qs - qs - qs -
TABLE 9
Formulations Formulation C Formulation D
Formulation E

Weight loss of PGMs (recovery) in mg/sq.in. 76.01 26.28 43.55
% wt. loss recovered (recovery of PGMs) relative to Formulation C 100.00 34.57 57.30
pH Initial 5.58 5.55 5.6
pH Final 5.55 5.55 5.55
TABLE 10

Advantages of Present invention:
One of the biggest advantages of the discovered process is that it can be carried out by just filling the equipment with the correct formulation at room temperature and leaving overnight for the process to take place and then just emptying the contents the next day and washing the equipment once. Where the equipment contains relatively thicker deposits, the process can be allowed to continue over two nights or over the weekend to reduce overhead costs. The cleaning formulation reaches all areas of the equipment (inside and outside of the tubes surfaces, shell inside surface, baffles etc.) and loosens the PGM particles easily. Typically, after the draining of the liquid the next day, the equipment is washed once or twice with ordinary water and a simple water jet to collect the remaining residues.
One of the advantages of the newly discovered method is that the PGMs in the equipment can be loosened by just filling the equipment by the developed method and kept overnight (12h to 16h). No high-pressure hydro-blasting is required. No mechanical cleaning is required. No major dismantling is required in this new method. Also, the residues of PGM being heavy in nature, they can be easily separated by simple filtration.
Discharge of the spent liquids into the effluent treatment plant can be done in existing facilities, as they are non-toxic. No separate effluent treatment is required, and the pH of the spent bath is within the discharge range allowed, which is an added advantage of this new process.
Another major advantage of this method is that the PGM residues can be easily separated by standard filtration and drying using commonly available equipment such as centrifugal dryers, Nutsche filters, pad filters etc.
Another major advantage of this method is that the base material of construction of the equipment is not attacked.
Another major advantage of this method is that the waste liquids from the non-acidic cleaning can be treated in the existing effluent treatment plant.
Another major advantage of this method is that standard precautions while working in chemical plants is sufficient. By this process, no additional occupational safety or health hazards, such as fume or hydrogen generation, are created.
Another advantage of this new process is that it is highly economical and uses easily available bulk chemicals.
, Claims:We claim,
1. A non-acidic composition for recovery of deposited platinum group metals from the instruments used in manufacturing of chemicals such as Nitric Acid and Caprolactam chemicals and any other chemicals starting with oxidation of ammonia to NOx, composition comprising of; alkali salt prepared by reacting a weak acid in 0.1 to 2.5 Mol/Lit concentration and strong alkali in 0.1 to 4.0 Mol/Lit concentration, characterized in that the pH of said alkali salt is between pH 5 to 6 using buffering agent.
2. The non-acidic composition as claimed in claim 1, wherein weak acid selected from Phosphonic acid; 1-Hydroxyethylidene-1,1-diphosphonic acid (Etidronic acid); Diethylenetriamine penta(methylene phosphonic acid); 2-Phosphonobutane-1,2,4-tricarboxylic acid; Amino(trimethylene phosphonic acid) and combinations thereof.
3. The non-acidic composition as claimed in claim 1, wherein strong alkali selected from Sodium hydroxide, potassium hydroxide and combination thereof.

4. The non-acidic composition as claimed in claim 1, wherein buffering agent selected from Acetates; Citrates; Phosphates; Oxalates; 2-[4-(2-hydroxyethyl)piperazin-1-yl]ethanesulfonic acid; (3-(N-morpholino)propanesulfonic acid); tris(hydroxymethyl)aminomethane (TRIS); Borates; Hydrogen phthalates; Dihydrogen orthophosphates; Alkali tartarates and combinations thereof.

5. A process for recovery of deposited platinum group metals from the instruments used in manufacturing of chemicals such as Nitric Acid and Caprolactam chemicals using non-acidic composition, said process comprising the following steps:
i. contacting said instruments used in manufacturing of chemicals with an alkali salt solution having pH between 5 to 6 for time between 5 minutes to 72 Hrs,
ii. Maintaining the temperature of solution at room temperature and, optionally, increasing the temperature of said solution from 20 to 60 Deg C to leach platinum group metals from instruments into alkali salt solution to obtained a alkali salt mixture,
iii. Separating alkali salt mixture from instrument and
iv. Recovering the dissolved platinum group metals from said alkali salt mixture using known suitable separation techniques.

6. The process for recovery of deposited platinum group metals as claimed in claim 5, wherein alkali salt solution is selected from the composition comprising weak acid in 2.0 to 4.5 Mol/Lit concentration and strong alkali in 1.0 to 5.0 Mol/Lit concentration.
7. The process for recovery of deposited platinum group metals as claimed in claim 6, wherein weak acid selected from Phosphonic acid; 1-Hydroxyethylidene-1,1-diphosphonic acid (Etidronic acid); Diethylenetriamine penta(methylene phosphonic acid); 2-Phosphonobutane-1,2,4-tricarboxylic acid; Amino(trimethylene phosphonic acid) and combinations thereof.
8. The process for recovery of deposited platinum group metals as claimed in claim 6, wherein strong alkali selected from Sodium hydroxide, potassium hydroxide and combination thereof.
9. The process for recovery of deposited platinum group metals as claimed in claim 5, wherein step ii) temperature selected between 20 to 40 Deg C.
10. The process for recovery of deposited platinum group metals as claimed in claim 5, wherein instruments selected from scrap metal instruments, dismantled instruments and in-line installed instruments.
11. The process for recovery of deposited platinum group metals as claimed in claim 10, wherein material of construction of instruments selected from mild steel, stainless steel 300 series, stainless steel 400 series and high nickel alloys such as Incoloy.
12. The process for recovery of deposited platinum group metals as claimed in claim 5, wherein a buffering agent is selected from Acetates; Citrates; Phosphates; Oxalates; 2-[4-(2-hydroxyethyl)piperazin-1-yl]ethanesulfonic acid; (3-(N-morpholino)propanesulfonic acid); tris(hydroxymethyl)aminomethane (TRIS); Borates; Hydrogen phthalates; Dihydrogen orthophosphates; Alkali tartarates and combinations thereof.