Description:

FORM-2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003

COMPLETE SPECIFICATION
[See section 10, Rule 13]

AN ANHYDROUS METAL CLEANING COMPOSITION AND A PROCESS FOR PREPARATION THEREOF

MCNROE CONSUMER PRODUCTS PVT. LTD, HAVING ITS OFFICE AT GODREJ GENESIS, UNIT 1204, PLOT XI, BLOCK EP & GP, SECTOR V, SALT LAKE CITY, BIDHANNAGAR, KOLKATA- 700091, WEST BENGAL, INDIA

THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED.

FIELD OF THE INVENTION
The invention relates to an anhydrous metal cleaning composition and its process for preparation.

BACKGROUND OF THE INVENTION
Metal utensils such as that made of copper, brass, iron, silver, stainless steel etc. used in household and industrial settings are prone to rusting and corrosion as these in contact with aqueous fluids. Hence, such metal utensils are required to be cleaned before and after use to remove the corrosion or rust that has been formed and deposited on the utensils.

WO 2006/136774 describes an acidic hard cleaning surface liquid cleaning composition comprising formic acid or sulfamic acid, at least one further acid selected from organic or inorganic acid and at least one nonionic surfactant. However, formic acid is considered harmful due its effect upon contact with skin or eyes and upon ingestion.

Metal cleaning compositions contain abrasives such as quartz, fine glass dust etc. for cleaning purposes. Cleaning compositions such as abrasive polishes and silver dips are time consuming in use and damage the metal surface from the abrasive due to their hardness or their possible detrimental effect on other metals.

Also, metal cleaning compositions contain surfactants and generally require water for cleaning and rinsing of the utensils during use of the composition. However, water may not always be available in quantities required for cleaning utensils. Also, while washing with water, utensils such as those made of copper, silver, and brass are required to be immediately wiped dry after washing to prevent formation of an oxidized metal film on the surface of the utensils that dulls its appearance. However, usually in households, utensils after washings are kept in open air for drying and are not wiped to remove the water.

There is a need for a metal cleaning composition that effectively cleans and shines the metal without damaging the metal surface. Also, there is a need for a composition that can work effectively with less or even absence of water.
SUMMARY OF THE INVENTION
The invention relates to an anhydrous metal cleaning composition comprising 70-85% w/w of dolomite as an abrasive, 5-15% w/w of China clay as a filler, 0.1-8.0% w/w of a metal oxide, 0.01-6.0% w/w of an alkali metal carbonate, 0.1-12.0% w/w of sand (mica), 0.1-18.0% w/w of citric acid and 5.0-15.0% w/w of oxalic acid or acetic acid, such that the total amount of the components is 100% w/w.

BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1: Graph comparing the ?E values for composition of Formulation 6 of the present invention and its individual components on cleaning of copper articles.

Figure 2: Graph comparing the ?E values for composition of Formulation 7 of the present invention and its individual components on cleaning of copper articles.

Figure 3: Graph comparing the ?E values for composition of Formulation 8 of the present invention and its individual components on cleaning of copper articles.

Figure 4: Graph comparing the ?E values for composition of Formulation 9 of the present invention and its individual components on cleaning of copper articles.

Figure 5: Graph comparing the ?E values for composition of Formulation 10 of the present invention and its individual components on cleaning of copper articles.

Figure 6: Graph comparing the ?E values for composition of Formulation 11 of the present invention and its individual components on cleaning of copper articles.

Figure 7: Graph comparing the ?E values for composition of Formulation 12 of the present invention and its individual components on cleaning of copper articles.

Figure 8: Graph comparing the ?E values for composition of Formulation 6 of the present invention and Comparative Formulations A-D on cleaning of copper articles.

Figure 9: Graph comparing the ?E values for composition of Formulation 6 of the present invention and available marketed composition on cleaning of copper articles.

Figure 10: Images of a copper article (glass) before and after cleaning with the composition of the present invention.

Figure 11: Images of a silver article (glass) before and after cleaning with the composition of the present invention.

Figure 12: Accelerated stability study data for Formula 6 of the present invention.

DETAILED DESCRIPTION OF THE INVENTION
In an aspect, the invention relates to an anhydrous metal cleaning composition comprising 70-85% w/w of dolomite as an abrasive, 5-15% w/w of China clay as a filler, 0.1-8.0% w/w of a metal oxide, 0.01-6.0% w/w of an alkali metal carbonate, 0.1-12.0% w/w of sand (mica), 0.1-18.0% w/w of citric acid and 5.0-15.0% w/w of oxalic acid or acetic acid, such that the total amount of the components is 100% w/w.

The term “filler” refers to a compound or substance that is added to aid in preparation of the composition. The term “abrasive” refers to a compound or substance that used to wear away the surface of softer, less resistant materials by grinding or rubbing. These terms are known to the person skilled in the art.

The alkali metal carbonate is selected from sodium carbonate, potassium carbonate, lithium carbonate or a combination thereof.

The metal oxide is selected from aluminium oxide, zinc oxide, titanium dioxide, chromium dioxide, iron oxide or a combination thereof.

The composition optionally includes a colour and a perfume.

In an embodiment, the composition comprises 70-85% w/w of dolomite, 5-15% w/w of China clay, 0.5-2% w/w of aluminium oxide, 0.01-3% w/w of sodium carbonate, 1-5% w/w of sand (mica), 3-8% w/w of citric acid and 5-10% w/w of oxalic acid such that the total amount of the components is 100% w/w.

In an embodiment, the anhydrous metal cleaning composition is a powdered solid. The pH of a 10% solution of the composition is in a range of around 4.0-6.0.

The metal cleaning composition provides for cleaning the surface of a metal selected from but not limited to brass, copper, silver, aluminium or steel.

The metal composition effectively cleans and shines metal articles (for example but not limited to utensils) with very less effort. Small trinkets that are normally hard to handle are cleaned efficiently and effectively.

The metal cleaning composition cleans heavily decorated silver as easily as plain silver. The silver is effectively cleaned without the need for polishing thereby, avoiding the mess and labor time required with conventional polishing compositions.

The composition includes mineral abrasives such as dolomite which is a mild abrasive. The metal cleaning composition is free of harsh abrasives such as quartz and is also free of surfactants. Thereby, the composition cleans and shines the metal article without damaging its surface. Also, as the composition does not include a surfactant, it can be effectively used to clean and shine metal articles with less water or even in absence of water. As the composition cleans in absence of washing with water, it avoids the need to wipe the articles after cleaning. Further, the composition is stable on storage. The components present in the composition are not harmful to skin. Thereby, the composition is safe to handle while not affecting the metal being cleaned.

In another aspect, the present invention relates to a process for preparing an anhydrous metal cleaning composition. The process comprises forming a mixture of the abrasive and the filler. Then metal oxide, alkali metal carbonate and sand (mica) are added to the mixture, followed by addition of citric acid and oxalic acid or acetic acid.

The process for preparation is quick and easy as there are less ingredients. The process can be easily scaled from a small to a large scale.

The process can be carried out in any mixer/blender known for mixing powder components. In an embodiment, the composition is prepared in a ribbon blender.

EXAMPLES
Example 1
The anhydrous metal cleaning composition of the present invention is described in Table 1 below.

Table 1
Formulation 1
Ingredient Quantity (% w/w)
Dolomite powder 80
China clay (300#) 14.69
Aluminium oxide 0.1
Sodium carbonate 0.01
Sand (mica) 0.1
Oxalic acid 5
Citric acid 0.1
Colour and perfume q.s.

Process for Preparation: Dolomite powder and China clay were added into a dry ribbon blender and mixed thoroughly. Then aluminium oxide, sodium carbonate and sand (mica) were added and mixed for 15 minutes. Subsequently, oxalic acid and citric acid was added into the ribbon blender followed by colour and mixed thoroughly for 15 to 20 minutes so that no lumps were formed. Then, perfume was added into the blender and mixed thoroughly for 15 to 20 minutes.

Examples 2-12
Tables 2 and 3 describes the anhydrous metal cleaning composition as per the invention (Formulations 2-12) with varying quantities of the components.

Table 2
Ingredient Quantity (% w/w)
Formulation 2 Formulation 3 Formulation 4 Formulation 5 Formulation 6
Dolomite powder 70 70 75 85 70
China clay (300#) 9 5 7 6 5
Aluminium oxide 4 8 0.5 1 2
Sodium carbonate 3 6 0.5 1 1
Sand (mica) 6 1 2 1 2
Oxalic acid 5 5 10 5 5
Citric acid 3 5 5 1 15
Colour and perfume q.s. q.s. q.s. q.s. q.s.

Table 3
Ingredient Quantity (% w/w)
Formulation 7 Formulation 8 Formulation 9 Formulation 10 Formulation 11 Formulation 12
Dolomite powder 70 70 70 70 70 70
China clay (300#) 5 5 5 5 5 5
Aluminium oxide 2 2 --- --- --- ---
Zinc oxide --- --- 2 --- --- ---
Titanium dioxide --- --- --- 2 --- ---
Chromium Dioxide --- --- --- --- 2 ---
Iron oxide --- --- --- --- --- 2
Sodium carbonate --- --- 1 1 1 1
Potassium carbonate 1 --- --- --- --- ---
Lithium carbonate --- 1 --- --- --- ---
Sand (mica) 2 2 2 2 2 2
Oxalic acid 5 5 5 5 5 5
Citric acid 15 15 15 15 15 15
Colour and perfume q.s. q.s. q.s. q.s. q.s. q.s.

Formulations 2-12 were prepared by the process described in Example 1.

Comparative Examples
Table 4 describes the composition of Comparative Formulations A-D.

Table 4
Ingredient Quantity (% w/w)
Comp. A Comp. B Comp. C Comp. D
Dolomite powder --- --- --- 76.5
China clay (300#) 59 68 72.8 15
Trisodium phosphate --- --- 1.2 1.8
Aluminium oxide --- --- --- ---
Sodium chloride/ Potassium chloride --- --- 17 ---
Sodium carbonate 30 16 --- ---
Sodium metasilicate/Potassium metasilicate 7 11 --- ---
Citric acid 4 3 6 6
Acetic acid --- 2 3 ---
Oxalic acid --- --- --- ---
Sand (mica) --- --- --- 0.7
Colour and perfume q.s. q.s. q.s. q.s.

Evaluation
I. Evaluation of cleaning effect of composition of the invention and its individual components
Formulations 6-12 of the present invention as described in Tables 2 and 3 above, were tested on rusted copper articles to evaluate the cleaning effect and compared with the cleaning effect of its individual components. The evaluation was carried out in presence and absence of washing with water.

The cleaning effect was ascertained by determining the ?E of the article before and after cleaning with the composition. The ?E value was determined by measuring the L, a, and b values of the CIELAB (lab color space) and then applying Equation 1 below. For better cleaning a higher ?E is desired. For copper articles the metal cleaning composition of the present invention provides a ?E value in a range of 20.36-21.15.

Equation 1

Where,
L1, a1, and b1 are the values before cleaning;
L2, a2, and b2 are the values after cleaning with the composition.

The L, a, and b values of the copper article before cleaning was as below:
L1 value = 70.44,
a1 value = 15.08,
b1 value =25.34.
Tables 5-11 below provides the L, a, b and ?E values of copper article after cleaning with Formulations 6-12 and its individual components.

Table 5
After cleaning
L2 value a2 Value b2 Value ?E Value
Formulation 6 88.23 12.1 15.89 20.36
Individual components
Dolomite 68.2 15.17 26.14 2.38
China clay 69.75 15.23 22.03 3.38
Aluminium oxide 67.14 11.97 18.01 8.62
Sodium carbonate 63.77 13.1 27.75 7.36
Sand (mica) 81.22 11.97 18.01 13.40
Oxalic acid 77.28 12.88 19.74 9.11
Citric Acid 79.37 13.21 20.86 10.16

Table 6
After cleaning
L2 value a2 Value b2 Value ?E Value
Formulation 7 87.88 10.88 15.74 20.35
Individual components
Dolomite 68.2 15.17 26.14 2.38
China clay 69.75 15.23 22.03 3.38
Aluminium oxide 67.14 11.97 18.01 8.62
Potassium carbonate 64.22 15.97 28.01 6.83
Sand (mica) 81.22 11.97 18.01 13.40
Oxalic acid 77.28 12.88 19.74 9.11
Citric Acid 79.37 13.21 20.86 10.16

Table 7
After cleaning
L2 value a2 Value b2 Value ?E Value
Formulation 8 87.77 10.1 17.75 19.56
Individual components
Dolomite 68.2 15.17 26.14 2.38
China clay 69.75 15.23 22.03 3.38
Aluminium oxide 67.14 11.97 18.01 8.62
Lithium carbonate 64.14 15.17 26.01 6.34
Sand (mica) 81.22 11.97 18.01 13.40
Oxalic acid 77.28 12.88 19.74 9.11
Citric Acid 79.37 13.21 20.86 10.16

Table 8
After cleaning
L2 value a2 Value b2 Value ?E Value
Formulation 9 88.37 11.21 17.86 19.81
Individual components
Dolomite 68.2 15.17 26.14 2.38
China clay 69.75 15.23 22.03 3.38
Zinc oxide 67.2 10.17 20.14 7.85
Sodium carbonate 63.77 13.1 27.75 7.36
Sand (mica) 81.22 11.97 18.01 13.40
Oxalic acid 77.28 12.88 19.74 9.11
Citric Acid 79.37 13.21 20.86 10.16

Table 9
After cleaning
L2 value a2 Value b2 Value ?E Value
Formulation 10 88.22 11.97 18.01 19.48
Individual components
Dolomite 68.2 15.17 26.14 2.38
China clay 69.75 15.23 22.03 3.38
Titanium dioxide 67.75 11.23 19.03 7.87
Sodium carbonate 63.77 13.1 27.75 7.36
Sand (mica) 81.22 11.97 18.01 13.40
Oxalic acid 77.28 12.88 19.74 9.11
Citric Acid 79.37 13.21 20.86 10.16

Table 10
After cleaning
L2 value a2 Value b2 Value ?E Value
Formulation 11 87.77 10.1 17.75 19.56
Individual components
Dolomite 68.2 15.17 26.14 2.38
China clay 69.75 15.23 22.03 3.38
Chromium dioxide 68.77 11.1 18.75 7.88
Sodium carbonate 63.77 13.1 27.75 7.36
Sand (mica) 81.22 11.97 18.01 13.40
Oxalic acid 77.28 12.88 19.74 9.11
Citric Acid 79.37 13.21 20.86 10.16

Table 11
After cleaning
L2 value a2 Value b2 Value ?E Value
Formulation 12 87.88 10.88 15.74 20.35
Individual components
Dolomite 68.2 15.17 26.14 2.38
China clay 69.75 15.23 22.03 3.38
Iron oxide 68.22 11.97 18.01 8.27
Sodium carbonate 63.77 13.1 27.75 7.36
Sand (mica) 81.22 11.97 18.01 13.40
Oxalic acid 77.28 12.88 19.74 9.11
Citric Acid 79.37 13.21 20.86 10.16

A graphical comparison of the ?E values is shown in Figure 1-7.

From the above results it was seen that ?E value for Formulations 6-12 of the present invention was significantly greater than that of its individual components. Thereby, Formulations 6-12 comprising all the components together provided a superior cleaning of copper articles than the individual components.

II. Evaluation of cleaning effect of composition of the invention and Comparative Formulations
The cleaning effect of Formulation 6 on rusted copper articles was determined and compared with that of Comparative Formulations A-D described above in Table 4.

The cleaning effect was ascertained by determining the ?E of the article before and after cleaning with the composition as described in point I, above.

The L, a, and b values of the copper article before cleaning was as below:
L1 value = 66.15,
a1 value = 16.31,
b1 value = 24.43.

Table 12 below provides the L, a, b and ?E values of copper article after cleaning with Formulation 6 and the Comparative Formulations A-D.

Table 12
Example After cleaning
L2 value a2 Value b2 Value ?E Value
Formulation 6 85.22 11.1 16.53 21.29
Comp. A 75.27 16.2 28.46 9.97
Comp. B 80.02 12.35 22.03 14.62
Comp. C 78.33 16.12 27.32 12.52
Comp. D 83.72 13.3 19.63 18.46

A graphical comparison of the ?E values of the compositions is shown in Figure 8.

Comparative Formulation A did not contain dolomite, aluminium oxide (metal oxide), oxalic acid or acetic acid, and sand (mica). Comparative Formulation A had the lowest ?E value. This shows that composition with only citric acid as the acid did not provide a good cleaning.

Comparative Formulation B did not contain dolomite, metal oxide, and sand (mica). Comparative Formulation B contained acetic acid and reduced the amount of alkali metal carbonate and citric acid to almost half of that present in Comparative Formulation A. Comparative Formulation B had higher ?E value than Comparative Formulation A. This shows that composition comprising both citric acid and acetic acid provided a better cleaning than composition containing citric acid as the only acid.

Comparative Formulation C did not contain dolomite, metal oxide, sodium carbonate (alkali metal carbonate), and sand (mica). Comparative Formulation C had a lower ?E value than Comparative Formulation B. This shows that presence of alkali metal carbonate along with citric acid and acetic acid or oxalic acid in the composition provided a better cleaning. Also, sodium chloride due to its hygroscopic nature resulted in a poor flowing product upon storage.

Comparative Formulation D did not contain metal oxide, oxalic acid or acetic acid, and alkali metal carbonate. Comparative Formulation D had ?E value which was more than 1.5 times of that obtained with Comparative Formulation A. This shows that presence of dolomite and sand (mica) in the composition provided a better cleaning.

Formulation 6 of the present invention contained aluminium oxide (metal oxide), dolomite, China clay, sodium carbonate (alkali metal carbonate), citric acid, oxalic acid, and sand (mica). This formulation had the highest ?E value. This shows that the composition of the present invention provided superior cleaning and shine of copper articles than composition of Comparative Formulations A-D lacking the presence of all the components.

III. Effect of different metal oxides, alkali metal carbonates, and acid
A. Metal oxide
Metal cleaning compositions with different metal oxides such as aluminium oxide, chromium dioxide, titanium dioxide, iron oxide and zinc oxide were evaluated to determine the effect of metal oxides on the cleaning effect of the composition.

The formulations were prepared based on the composition described in Formulation 6 and aluminium oxide was replaced with chromium dioxide, titanium dioxide, iron oxide or zinc oxide.

The cleaning effect was ascertained by determining the ?E of the copper article before and after cleaning with the composition as described in point I, above.

The L, a, and b values of the copper article before cleaning was as below:
L1 value = 70.44,
a1 value = 15.08,
b1 value =25.34.

Table 13 below provides the L, a, b and ?E values of copper article after cleaning with formulations containing different metal oxides.

Table 13
Formulation 6 containing metal oxide After cleaning
L2 value a2 Value b2 Value ?E Value
Aluminium Oxide 88.23 12.1 15.89 20.36
Chromium Dioxide 87.77 10.1 17.75 19.56
Titanium Dioxide 88.22 11.97 18.01 19.48
Iron Oxide 87.88 10.88 15.74 20.35
Zinc Oxide 88.37 11.21 17.86 19.81

From Table 13, it was seen that ?E value for the compositions containing chromium dioxide, titanium dioxide or iron oxide was similar to that obtained for Formulation 6 containing aluminium oxide. Thus, the composition containing any of the described metal oxides provided a superior cleaning effect.

Also, a superior cleaning effect can be achieved by a composition containing a combination of metal oxides.

B. Alkali Metal Carbonate
Metal cleaning compositions with different alkali metal carbonates such as lithium carbonate, sodium carbonate and potassium carbonate were evaluated to determine the effect of alkali metal carbonates on the cleaning effect of the composition.

The formulations were prepared based on the composition described in Formulation 6 and sodium carbonate was replaced with lithium carbonate or potassium carbonate.

The cleaning effect was ascertained by determining the ?E of the copper article before and after cleaning with the composition as described in point I, above.

The L, a, and b values of the copper article before cleaning was as below:
L1 value = 70.44,
a1 value = 15.08,
b1 value =25.34.

Table 14 below provides the L, a, b and ?E values of copper article after cleaning with formulations containing different alkali metal carbonates.

Table 14
Formulation 6 containing alkali metal carbonates After cleaning
L2 value a2 Value b2 Value ?E Value
Sodium carbonate 88.23 12.1 15.89 20.36
Lithium carbonate 87.77 10.1 17.75 19.56
Potassium carbonate 87.88 10.88 15.74 20.35

From Table 14, it was seen that ?E value for the compositions containing potassium carbonate or lithium carbonate was similar to that obtained for Formulation 6 containing sodium carbonate. Thus, the composition containing any of the described alkali metal carbonates provided a superior cleaning effect.

Also, a superior cleaning effect can be achieved by a composition containing a combination of alkali metal carbonates.

C. Acid (Oxalic acid or Acetic acid)
Metal cleaning compositions with citric acid in combination with either oxalic acid or acetic acid were evaluated to determine the effect of either of the combination on the cleaning effect of the composition.

The formulations were prepared based on the composition described in Formulation 6 and oxalic acid was replaced with acetic acid.

The cleaning effect was ascertained by determining the ?E of the copper article before and after cleaning with the composition as described in point I, above.

The L, a, and b values of the copper article before cleaning was as below:
L1 value = 70.44,
a1 value = 15.08,
b1 value =25.34.

Table 15 below provides the L, a, b and ?E values of copper article after cleaning with formulations containing different alkali metal carbonates.
Table 15
Formulation 6 containing a combination of citric acid with After cleaning
L2 value a2 Value b2 Value ?E Value
Oxalic acid 88.23 12.1 15.89 20.36
Acetic acid 87.77 10.1 17.75 20.45

From Table 15, it was seen that ?E value for the compositions containing citric acid in combination acetic acid was similar to that obtained for Formulation 6 containing citric acid in combination with oxalic acid. Thus, the composition containing either a either oxalic acid or acetic acid in combination with citric acid provided a superior cleaning effect.

Also, a superior cleaning effect can be achieved by a composition containing both citric and oxalic acid in combination with citric acid.

IV. Evaluation of cleaning effect of composition of the invention and Available Marketed Composition
The cleaning effect of Formulation 6 on rusted copper articles was evaluated and compared with that of an available marketed composition (Pitambari® shining powder).

The cleaning effect was ascertained by determining the ?E of the article before and after cleaning with the composition as described in point I, above.

The L, a, and b values of the copper article before cleaning was as below:
L1 value = 70.44,
a1 value = 15.08,
b1 value =25.34.

Table 16 below provides the L, a, b and ?E values of copper article after cleaning with Formulation 6 and the marketed composition.

Table 16
Example After cleaning
L2 value a2 Value b2 Value ?E Value
Formulation 6 88.23 12.1 15.89 20.36
Marketed Composition 84.77 11.54 17.07 16.92

A graphical comparison of the ?E values of the compositions is shown in Figure 9.

From the results in Table 16, it was seen that Formulation 6 provided a significantly greater ?E value and thereby a better cleaning effect of copper articles than the marketed composition.

Figure 10 shows the images of a copper glass before and after cleaning with Formulation 6. Figure 11 shows the images of a silver glass before and after cleaning with Formulation 6. From the figures it was seen that the surface of the articles was smooth. Thus, the composition of the present invention did not damage the metal surface.

From the results, it can be inferred that the superior cleaning is due to the combined effect of presence of dolomite, metal oxide, alkali metal carbonate, citric acid, oxalic or acetic acid and sand (mica) in the anhydrous metal cleaning composition.

Stability Study
The composition of Formulation 6 of the present invention was evaluated for storage stability by subjecting it to accelerated stability testing. The results of the accelerated stability studies is shown in Figure 12.

As shown in the figure the parameters of physical appearance, bulk density, pH (10% solution) and loss on drying for Formulation 6 after storage up to 3 months at temperatures of 8-10°C, 25°C and 45°C were within permissible limits. This shows that the Formulation was stable on storage.

The foregoing description of the invention has been set merely to illustrate the invention and is not intended to be limiting. Since modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to person skilled in the art, the invention should be construed to include everything within the scope of the disclosure.
, C , Claims:
1. An anhydrous metal cleaning composition comprising 70-85% w/w of dolomite as an abrasive, 5-15% w/w of China clay as a filler, 0.1-8.0% w/w of a metal oxide, 0.01-6.0% w/w of an alkali metal carbonate, 0.1-12.0% w/w of sand (mica), 0.1-18.0% w/w of citric acid and 5.0-15.0% w/w of oxalic acid or acetic acid, such that the total amount of the components is 100% w/w.

2. The composition as claimed in claim 1, wherein the alkali metal carbonate is selected from sodium carbonate, potassium carbonate, lithium carbonate or a combination thereof.

3. The composition as claimed in claim 1, wherein the metal oxide is selected from aluminium oxide, zinc oxide, titanium dioxide, chromium dioxide, iron oxide or a combination thereof.

4. The composition as claimed in claim 1, comprising 70-85% w/w of dolomite, 5-15% w/w of China clay, 0.5-2% w/w of aluminium oxide, 0.01-3% w/w of sodium carbonate, 1-5% w/w of sand (mica), 3-8% w/w of citric acid and 5-10% w/w of oxalic acid such that the total amount of the components is 100% w/w.

5. The composition as claimed in any one of the claims 1 to 4 wherein the composition is in form of a powdered solid.

6. A process for preparing an anhydrous metal cleaning composition as claimed in claim 1, the process comprising:
forming a mixture of the abrasive and the filler;
adding the metal oxide, alkali metal carbonate and sand (mica) to the mixture; and
adding citric acid and oxalic acid or acetic acid.

7. The composition as claimed in any one of claims 1 to 5 for cleaning a surface of a metal selected from brass, copper, silver, aluminium or steel.