FORM 2
THE PATENTS ACT 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(See Section 10; rule 13)
TITLE OF THE INVENTION
A process for the preparation of synthetic tanning composition
from solid waste


APPLICANTS
Tata International Limited an Indian company having its registered
office at Block 'A' Shivsagar Estates, Dr. Annie Besant Road, Worli
Mumbai 400 018, Maharashtra , India
INVENTORS
Subramani Saravanabhavan, Anupama Pati, Rajiv Bhirud and Opender Kumar Kaul all of Tata International Limited
an Indian company having its registered office at
Block 'A' Shivsagar Estates, Dr. Annie Besant Road, Worli
Mumbai 400 018, Maharashtra , India
PREAMBLE TO THE DESCRIPTION
The following specification particularly describes the invention and the manner in which it is to be performed


FIELD OF INVENTION
The present invention relates to a novel process for the preparation of synthetic tanning composition from solid waste such as coal ash, leather shaving dust. More particularly, the present invention provides a process for the manufacture of synthetic tanning agent from coal ash for leather processing.
BACKGROUND OF INVENTION
Coal ash is the most abundant waste material. Disposal of coal ash creates a major stumbling block to the industrialists. Coal ash such as fly ash and bottom ash are solid wastes generated from coal-fired boilers. It contains both organic and inorganic components. Unburned carbon is the organic part of coal ash and metal ions such as are the
inorganic parts of coal ash (Bhanarkar et al., Fuel, 87, 2095-2101, 2008). The composition of metal ions varies with origin and type of coal fuel used in the boiler. Less amount of heavy metals are released from bottom ash than from fly ash (Rios et al., Journal of Hazardous Materials, 156, 23-35, 2008). Hence, bottom ash has been employed in the construction of roads and bridges. It has been reported that alkaline fly ashes could serve as a stabilizer or a binding reagent for fixing heavy metals and nutrients present in hazardous and organic wastes (Shende et al., Resource Conservation and Recovery, 12, 221-228, 1994). Major component of coal ash is the metal oxides which make the ash usable for the manufacture of bricks and cements. Fly ash and bottom ash materials have been reported as adsorbent for the removal of dyes and heavy metal ions in the wastewater (Dincer et al., Journal of Hazardous Materials, 141, 529-535, 2007). Lisowyj reported
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that the method of extraction of iron, aluminium and titanium from coal ash (US Patent No. 4567026, 1986). Hill et al established the process for the extraction of pure aluminium metals from coal ash (US Patent No. 4243640, 1981). Preparation of aluminium sulfate salt from coal ash has been reported by Malybaeva, et al (US Patent No. 6214302, 2001). Russ et al have been established the method for separating and recovering silica, aluminium and iron from fly ash, mineral ores and mine tailings (US Patent No. 4539187, 1985).
Solid wastes containing chromium, more so those generated immediately after the tanning process like shaving dusts continue to pose significant challenges. The tanned wastes primarily consist of chromium and protein. They include shavings, trimmings and splitting wastes. Use of chrome shavings in the manufacture of leather boards, insulators, building materials, fibrous sheets and shoe soles have been reported (Saravanabhavan et al., Journal of Society Leather Technologist and Chemists, 88, 202-207, 2004). During the last decade there are reports on the separation of chromium and protein from such wastes for industrial applications. The costing for such methodologies has also been worked out (Sreeram and Ramasami, Resources, Conservation and Recycling, 38, 185-212,2003).
Consequently, the inventors of the present invention realized that there exists a dire need to develop a method, which is able to utilize the solid waste such as coal ash and chrome shaving. The present invention aims at providing an improved synthetic tanning agent for leather processing, thereby reducing the environmental impact of the solid wastes such as coal ash and chromium containing solid wastes.
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OBJECTS OF INVENTION
The main object of this invention is thus to provide an improved process for the preparation of synthetic tanning agent from solid wastes, which precludes the drawbacks stated above.
Another object of this invention is to provide synthetic tanning agent that reduce the cost of synthetic tanning agent.
Yet another object of this invention is to prepare a synthetic tanning agent from coal ash and chromium containing solid wastes.
Yet another object of this invention is to improve an enhanced characteristic and quality of leather after tanning.
Yet another object of this invention is to reduce the environmental impact of the solid wastes.
Yet another object of this invention is to complexation of metal ions with organic materials for improving leather characteristics.
SUMMARY OF INVENTION
Accordingly, the present invention provides a process for the preparation of synthetic tanning composition from solid waste comprising the steps of:
(a) heating coal ash with an aqeous acidic solution;
(b) separating undissolved and suspended impurities therefrom;
(c) treating said aqueous acidic extract with a complexing agent to produce metal complexes and
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(d) treating said complex with a base till the pH reach 2.5 to 3 to obtain a tanning composition.
The solid wastes used for the preparation of synthetic tanning agent may be such as fly ash, bottom ash and chrome shaving either alone or in combination.
The amount of water used for the preparation of synthetic tanning agent may be in the range of 100 - 300% w/w based on weight of solid wastes.
The acid used for the preparation of synthetic tanning agent may be such as sulphuric acid, hydrochloric acid, nitric acid, formic acid, oxalic acid either alone or in combination.
The amount of acid used for the preparation of synthetic tanning agent may be in the range of 10 - 30% w/w based on weight of solid wastes.
The heating temperature for the preparation of synthetic tanning agent may be in the range of 40 - 105°C.
The complexing agent used for the preparation of synthetic tanning agent may be such as phenol sulfonic acid, naphthalene sulfonic acid, urea, glycerine, natural polyphenols such as wattle, gambier, quebracho and formaldehyde either alone or in combination.
The amount of additives used for the preparation of synthetic tanning agent may be in the range of 10 - 40% w/w based on weight of solid wastes.
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The alkali used for the neutralization of synthetic tanning agent may be such as sodium hydroxide, sodium silicate and sodium bicarbonate either alone or in combination.
The amount of alkalies used for the neutralization of synthetic tanning agent may be in the range of 5 - 25% w/w based on weight of solid wastes.
DESCRIPTION OF INVENTION
The process of the present invention is described below in detail. Solid waste is charged into the thermo static three-necked reactor. To this water 100-300% and acid 10 - 30% (w/w based on the solid waste) is added and continuously stirred and heated to temperature range of 70 -105°C for period of not more than 3 h. Aqueous acid and coal ash mixture is filtered and filtrate charged into another thermo static three necked reactor. To this additive 10 - 40% (w/w based on the solid waste) is added, stirred continuously and heated 40 - 105°C for 2 h. The resultant mixture is cooled to room temperature. The cooled solution is neutralized to a pH 2.5 - 3.0 using 10 - 25% w/w alkali or mixture of alkalis (based on the weight of the solid waste) with continuous stirring.
The inventive step of the present invention lies in the preparation of a synthetic tanning agent by complexing the aqueous solution of coal ash with additives such as phenol sulfonic acid, naphthalene sulfonic acid, urea, glycerine, natural polyphenols such as wattle, gambier, quebracho formaldehyde. Thus the obtained synthetic tanning agent provides better properties to the final tanned leather.
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The invention is described in detail in the following examples, which are provided by way of illustration only and therefore should not be construed to limit the scope of the present invention.
Example 1
In a thermostatic three-necked reactor, 1000 g of dry bottom ash containing aluminium and iron metal oxides of 32.2% and 6.4%, respectively was treated with 2000 ml water and 200 g sulphuric acid at a constant temperature of 80°C with continuous stirring for period of 2 h. Aqueous mixture filtered and filtrate weight was found to be 1800 g. Filtrate was transferred to another thermostatic three necked reactor. To this 80 g phenol sulphonic acid, 100 g naphthalene sulphonic acid and 100 g Urea were added with continuous constant stirring for 2h at a temperature of 80°C. The mixture is cooled to 40°C and 20 g of 37% formaldehyde added slowly for period of 3 h. Temperature of mixture raised to 70°C with continuous stirring for 30 min to remove free formaldehyde. Then, the mixture was cooled to room temperature and neutralized to a pH 2.5 using 160 g sodium hydroxide with continuous stirring. The prepared synthetic tanning agent unloaded from the reactor and stored in a 5 kg plastic container.
Example 2
In a reaction vessel, 500kg of dry bottom ash and 500kg dry fly ash was treated with 3000 L water and 250kg sulphuric acid 50kg oxalic acid at a constant temperature of 90oC with continuous stirring for period of 2 h. Aqueous mixture filtered and filterate weight was found to be 2600kg.
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Filtrate was transferred to another thermostatic three necked reactor. To this 180kg wattle was added with continuous constant stirring for 2h at a temperature of 60°C. The mixture was cooled to 40°C and 20kg of 37% formaldehyde added slowly for period of 3 h. Temperature of mixture raised to 70°C with continuous stirring for 30 min to remove free formaldehyde. Then, the mixture was cooled to room temperature and neutralized to a pH 3.0 using 100kg sodium hydroxide and 80kg sodium bicarbonate with continuous stirring. The prepared synthetic tanning agent unloaded from the reactor and stored in a container.
Example 3
In a thermostatic three-necked reactor, 1000 g dry fly ash was treated with 1000 ml water and 80 g sulphuric acid and 20 g oxalic acid at a constant temperature of 100°C with continuous stirring for period of 2 h. Aqueous mixture filtered and filterate weight was found to be 700 g. Filtrate was transferred to another thermostatic three necked reactor. To this 390 g Urea was added with continuous constant stirring for 2h at a temperature of 60°C. The mixture was cooled to 40°C and 10 g of 37% formaldehyde added slowly for period of 3 h. Temperature of mixture raised to 70°C with continuous stirring for 30 min to remove free formaldehyde. Then, the mixture was cooled to room temperature and neutralized to a pH 2.5 using 45 g sodium hydroxide and 5 g sodium silicate with continuous stirring. The prepared synthetic tanning agent unloaded from the reactor and stored in a 2 kg plastic container.
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Example 4
In a thermostatic three-necked reactor, 800 g dry bottom ash and 200 g dry chrome shaving were treated with 2000 ml water and 100 g sulphuric acid, 100 g hydrochloric acid, 50 g nitric acid and 50 g formic acid at a constant temperature of 105°C with continuous stirring for period of 2 h. Aqueous mixture filtered and filtrate weight was found to be 2100 g. Filtrate was transferred to another thermostatic three necked reactor. To this 90 g Urea and 10 g glycerine were added with continuous constant stirring for 2h at a temperature of 60°C. Then, the mixture was cooled to room temperature and neutralized to a pH 2.5 using 150 g sodium hydroxide and 5 g sodium bicarbonate with continuous stirring. The prepared synthetic tanning agent unloaded from the reactor and stored in a 5 kg plastic container.
Example 5
In a thermostatic three-necked reactor, 1000 g dry bottom ash was treated with 2000 ml water and 300 g sulphuric acid at a constant temperature of 80°C with continuous stirring for period of 2 h. Aqueous mixture filtered and filterate weight was found to be 1800 g. Filtrate was transferred to another thermostatic three necked reactor. To this 130 g wattle, 100 g gambier, 50 g quebracho, 50 g urea and 20 g glycerine were added with continuous constant stirring for 2h at a temperature of 60°C. Then, the mixture was cooled to room temperature and neutralized to a pH 2.5 using 200 g sodium hydroxide and 50 g sodium bicarbonate with continuous stirring. The prepared synthetic tanning agent unloaded from the reactor and stored in a 5 kg plastic container.
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Example 6
In a reaction vessel, 1000 kg dry bottom ash was treated with 3000 L water and 300 kg sulphuric acid at a constant temperature of 80°C with continuous stirring for period of 2 h. Aqueous mixture filtered and filterate weight was found to be 2300 kg. Filtrate was transferred to another thermostatic three necked reactor. To this 100 kg wattle, 100 kg gambier, 50 kg quebracho, 50 kg urea and 20 kg glycerine were added with continuous constant stirring for 2h at a temperature of 60°C. The mixture was cooled to 45°C and 30 kg of 37% formaldehyde added slowly for period of 3 h. Temperature of mixture raised to 70°C with continuous stirring for 30 min to remove free formaldehyde. Then, the mixture was cooled to room temperature and neutralized to a pH 2.5 using 200 kg sodium hydroxide and 50 kg sodium bicarbonate with continuous stirring. The prepared synthetic tanning agent unloaded from the reactor and stored in a container.
Example 7
In a thermostatic three-necked reactor, 800 g dry bottom ash and 200 g dry chrome shaving was treated with 1500 ml water and 150 g sulphuric acid and 150g oxalic acid at a constant temperature of 100°C with continuous stirring for period of 2 h. Aqueous mixture filtered and filterate weight was found to be 1000 g. Filtrate was transferred to another thermostatic three necked reactor. To this 350 g Urea and 50 g glycerine were added with constant stirring for 2h at a temperature of 60°C. Then, the mixture was cooled to room temperature and neutralized to a pH 2.5 using 100 g sodium hydroxide and 25 g sodium silicate with continuous stirring. The prepared
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synthetic tanning agent unloaded from the reactor and stored in a 2 kg plastic container.
Example 8
In a thermostatic three-necked reactor, 800 g of dry bottom ash and 200g fly ash was treated with 2000 ml water and 300 g sulphuric acid at a constant temperature of 80°C with continuous stirring for period of 2 h. Aqueous mixture filtered and filterate weight was found to be 1900 g. Filtrate was transferred to another thermostatic three necked reactor. To this 25 g phenol sulphonic acid, 25 g naphthalene sulfonic acid, 25 g wattle, 250 g Urea, 50 g glycerine were added with continuous constant stirring for 2h at a temperature of 80°C. The mixture is cooled to 40°C and 25 g of 37% fonnaldehyde added slowly for period of 3h. Temperature of mixture raised to 70°C with continuous stirring for 30 min to remove free formaldehyde. Then, the mixture was cooled to room temperature and neutralized to a pH 2.5 using 145 g sodium hydroxide and 100 g sodium bicarbonate with continuous stirring. The prepared synthetic tanning agent unloaded from the reactor and stored in a 5 kg plastic container.
The following are the advantages of the present invention
Utilizes solid wastes for synthetic tanning agent preparation
This product enhances the bulk characteristics of leathers after tanning
Reduces the environmental impact of solid wastes
Low cost of production
This process hardly requires any complicated control measures
Suitable for all kinds of raw materials.
Non-toxic nature of product
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WE CLAIM
1. A process for the preparation of synthetic tanning composition from
solid waste comprising the steps of:
(a) heating coal ash with an aqeous acidic solution;
(b) separating undissolved and suspended impurities therefrom;
(c) treating said aqueous acidic extract with a complexing agent to produce metal complexes and
(d) treating said complex with a base till the pH reach 2.5 to 3 to obtain a tanning composition.

2. The process as claimed in claim 1, wherein said solid waste is fly ash, bottom ash, leather shaving dust and chrome shaving either alone or in combination with each other.
3. The process as claimed in claims 1 and 2, wherein said aqueous acidic solution contains 10 to 30% w/w based on the solid waste of an acid selected from sulphuric acid, hydrochloric acid, nitric acid, formic acid and oxalic acid either alone or in combination in 100 to 300% w/w of water based on the solid waste.
4. The process as claimed in claims 1 to 3, wherein the solid waste and aqueous acidic solution mixture is heated to a temperature ranging from 40oC to 105oC for a period of about 2 hours.
5. The process as claimed in claims 1 to 4, wherein said metal complexing agent is selected from phenol sulfonic acid, naphthalene sulfonic acid, urea, glycerine, natural polyphenols such as wattle,
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gambier, quebracho and formaldehyde either alone or in combination.
6. The process as claimed in claims 1 to 5, wherein the amount of complexing agent ranges from 10 - 40% w/w based on the weight of solid waste. ,
7. The process as claimed in claims 1 to 6, wherein the base for treating the metal complexes is selected from sodium hydroxide, sodium silicate and sodium bicarbonate either alone or in combination.
8. The process as claimed in claims 1 to 7, wherein the base ranges from 10 - 25% w/w based on the solid waste.
9. A process for the preparation of synthetic tanning agent substantially as herein described with particular reference to the examples.
Dated 18th September 2008
TATA INTERNATIONAL LIMITED By their Agent and Attorney

(KARUNA GOLERIA) of DePENNING & DePENNING
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