2. Technical Field
2.1 Metallurgy - Mineral Processing
3. Prior Art
Alumina or the oxide of Aluminium with chemical formula Al2O3 occurs in abundance on
our earth. But its occurrence in association with other minerals hinders its usage for many
important applications and thus the minerals with alumina need to be purified/refined so
as to enhance the alumina content.
An important application of alumina is for production of Aluminium metal and it forms
the bulk of its usage, globally.
Conventionally, alumina is extracted from Bauxite using the Bayer's Process; where in the
Alumina of the Bauxite is selectively dissolved in Caustic Soda and is recovered on
precipitation from the solution.
Though attempts have been made to extract Alumina from some Alumina bearing clays,
but by far, Bauxite remains the only industrial source of Alumina.
Depending upon the characteristics & alumina content, its mineralogy and content of
associated minerals/oxides; various variants of Bayer's Process are in vogue. However,
one thing that remained unchanged is that virgin ore/mineral is used for extraction of
alumina on commercial basis. Further the ore is specifically mined for this purpose.
Note:- Any mineral becomes an ore if it yields favorable Techno-economics in subsequent
processing and thus mineral or ore are interchangeably used in this write-up.
4. Drawbacks of Prior Art
As on date, Bauxite, as virgin ore, is used for extraction of alumina on commercial basis. Mining of Bauxite on such commercial scale calls for deforestation and thus its impact on environment in addition to the cost mining and material handling.
5. The Invention :- 5.1 Patent application submitted here-in is for an innovative idea of
using waste, from coal related activities like mining, beneficiation, burning and
gasification etc; as an alternative to Bauxite and is titled as: - 'Alumina from Coal
Waste'.
5.2 Waste from Coal can be broadly classified in four types, viz.
A. Ash obtained on burning of Coal
B. Residue of Coal's Gasification process
C. Tailings of Coal Washeries
D. Over-burden of Coal Mines etc.
This patent application restricts its coverage to these four types of wastes generated on usage of coal for the sake of brevity but such coverage may include any other type/class of waste associated with mining and/or utilization of coal.
5.3 As is widely known, lot of non-carbonaceous materials, both organic & inorganic are
associated with coal mined from the mines. While there are commercial methods to
extract/exploit the non-carbonaceous organic materials, the inorganic ones are dumped as
waste. The waste so dumped is an additional environmental hazard.
5.4 Silica constitutes the bulk of inorganic waste. Among the others is Alumina and inventive concept of this Patent Application is 'extraction of this Alumina' and in turn extracting the mineral value of the waste.
5.5 Bayer's Process of Extraction of alumina is contemplated for extraction of alumina value of coal's waste. The only difference will be that instead of Bauxite, its feedstock will be coal's waste like, but not limited to, the ones stated in para 5.2 - A to D.
6. Benefits of the Invention
The invention titled 'Alumina from Coal Waste' puts to use the waste from mining/beneficiation and/or burning/gasification of coal. It provides the following benefits:-
6.1 Being waste, it is available almost at no cost.
6.2 It will also provide the added benefit of environmental protection, as it obviates the deforestation associated with mining of bauxite, equivalent of the alumina value.
6.3 There will be overall reduction in quantity of waste with savings in handling and disposal cost and reduced environmental hazards.
7. Applicability:-The invention will find application in areas with availability of coal waste like :-
A. Thermal Power Plants
B. Coal Mines
C. Coal Washeries
D. Coal Bed Gasification sites etc
and substitute this waste for bauxite to extract the alumina value of such waste.

8. Claim/s
8.1 Patent application submitted here-in is for an innovative idea of using waste, from coal related activities like mining, beneficiation, burning and gasification etc; as an alternative to Bauxite and is titled as: - 'Alumina from Coal Waste'.
8.2 The invention contemplates substitution of bauxite with coal's waste like ash, tailings and overburden etc for extraction of alumina using the conventional Bayer's Process.
8.3 Such substitution does not call for any new technology and thus can be implemented in short time.
8.4 Since the raw material for extraction of alumina value is a waste of another industrial, it will yield all the benefits associated with putting the waste to use like:-
A. Available at no cost
B. Benefit of environmental protection, as it obviates deforestation associated with mining
of bauxite, equivalent of the alumina value.