FIELD OF INVENTION:-
This invention relates to the field of exploration and mining of heavy minerals and rare earth elements. More particularly this invention relates to the mining and exploration of coastal sands for their rare earth contents and harnessing them. Still particularly this invention relates to the appropriate method of separating, extracting and filtering of heterogenic heavy mineral compositions from coastal sand.
BACKGROUND OF INVENTION:-
As its well known that India, has a vast coastline. The sea coasts of India can be described as repositories of massive wealth of mineral ores especially, Heavy minerals, as they are termed, the minerals such as Ileminite, Rutile, Garnet, Zircon, Sillimanite etc because of their higher specific gravities of more than 2.89. These are very valuable in terms of economical values as they are very much useful to humankind for various applications as an alternate to well known metals and non metals due to the highly specific properties exhibited by these heavy minerals which are also rare earth minerals.
It must be also noted that as of now, vast quantities of coastal sands, which are occurring in Indian coastlands in offshore areas of up to 1 kilometre from the sea coast are being dredged by various agencies ( both Governmental and non-Governmental) and are simply wasted as only a miniscule portion of the mineral wealth, especially the rare earth minerals are extracted from these sands with a whopping quantity of the rare earth mineralss contained in these coastal sands are simply unutilized and hence going as waste. This colossal waste, cannot be afforded by our country and every effort is to be made to harness the vast potential of rare earth minerals contained in these coastal sands and utilize them for the benefit of mankind and also for enhancing the Economic potential of the nation. Hence, there requires a critical need of a suitable method and process for appropriate harnessing of heavy minerals that are present in the coastal sands of the country.
The heavy minerals like ilemenite, garnet, magnetite, zircon, rutile, monazite and sillimante, xenotime and diamonds occur in the coastal sands of India. These are also extended in to offshore coastal areas up to 1 km from the coast line. It can be very well observed that at present, these mineral rich areas are not exploited to a large extent. These coastal zones are future mining areas and these minerals are strategic importance and are called future

minerals. Hence this effort involving indigenous exploratory initiatives for these minerals is taken up.
The detailed description of these minerals and their economic significance is discussed below.
Definition of placer Minerals:
Placer minerals are the heavy minerals that have specific gravity more than 2.8 (that of bromofarm). These are also called as heavy minerals. These are the product of mechanical and chemical disintegration of the rocks that are transported by the water from the place of disintegration and deposited in suitable sites. These minerals generally have an economical value. Example: Diamonds, gold, tin, ilmenite, rutile garnet, sillimanite, zircon, monazite and magnetite.
These placers are called with different names like, river placers, beach placers and colluvial and Aeolian placers based on the mode of their transport. River placers are the minerals that are occur in the rivers and the beach placers are he placers that occur along the beaches and the colluvial placers are deposited due to glaciers and the Aeolian placers are the placers that

are deposited by the wind.
The formation, accumulation and concentration of these minerals in each deposit are mainly controlled by (a) Provenance rocks (b) Climate inducing deep weathering (c) river (transport) system (d) coastal geomorphology (e) wave configuration incident to the coast and (f) long shore current, waves and tide.
The placer minerals are further divided in to light heavy minerals with specific gravity up to 5 and the heavy minerals that are having a specific gravity more than 5 and up to 20. The list of heavy minerals and their specific gravities are listed below:
Beach Placers :- Beach placers are the heavy minerals that are deposited along the beaches. These are derived from the mechanical disintegration of the rocks and are transported by the rivers into the sea. The Sea further disintegrated the sediments in to minerals by its waves by pounding action and further the waves separated the heavies from the light minerals and deposits on the shore. The minerals are depends on the nature of the sediment that is brought into the sea by the rivers hence the beach placers are having connection with the hinterland rocks.
Advantages to look for offshore beach placers: -
The above said minerals are available in the nature in the rocks like, igneous, sedimentary and metamorphic. The quantities of these minerals within these rocks are very less say .05% and their grain size is also small. However, larger grains may be common in some placers but not of commercial quantities. Further their distribution within these rocks is not uniform. Hence, it cannot form a rich deposit unlike any metallic or non-metallic deposits. More so, the mining of these minerals even though concentrated in some rocks is difficult which needs crushing and separation of huge rock mass in to small size to liberate these minerals. More so, crushing may cause the damage to natural crystal faces of the minerals and cost is high and creates environmental problems.
The nature, mainly in the form of the weathering and transportation by, streams, rivers have liberated these minerals from the huge rock mass, worked continuously for millions of years and dumped into the sea. The sea with the wave action have further separated as per their specific gravity and deposited all the minerals en- mass in the suitable locales. This process is very costly which is done by the nature itself.

This natural process has done major work for us and what we have to do is further separate
the minerals in to pure fractions. Hence, gravity and other mechanical methods are used to
separate these minerals from other unwanted minerals, which are available in one single
place, the off shore beaches.
Uniqueness of offshore Beach placer Deposits: -
The beach placers have many unique features which are characteristic of its own and are
pointed below:
1. The assemblage of 6 to 8 minerals are found in the free state unlike in the rocks
2. The natural process like weathering and transportation by the rivers have helped in the separation of minerals without effecting their crystal structure or its chemical composition
3. These minerals have varying physical properties like specific gravity and the magnetic susceptibility that lend them effective separation by less expensive methods.
4. These deposits are huge and replenish able.
Nature and Minerals Species available: The grain size of the beach placer minerals is very
small having a range of size from 475 microns to 73 microns. These are measured generally
in mesh sizes like 40 mesh (475 microns) and 230 mesh (73 microns). These are also termed
as coarse and medium and fine-grained depend up to the grain size.
The mineral species that occur in any beach dunes are dependent on the hinterland geology
(rock types) and the river, drainage system in the area and morphology and the currents in the
sea.
Generally in India magnetite, ilmenite, rutile, leucoxene, monazite, zircon, garnet, sillimanite,
kyanite, xenotime and micro diamonds are the heavy minerals occurring. At places like in
KG (Krishna Godavari) basin the author reported the micro diamonds and xenotime.
Uses: The use of the heavy minerals depend nt upon the grain size and Chemical
composition. The grain size of the mineral helps in their physical separation from other co
existing minerals and the chemical composition of the mineral being unique helps in using
them in different industries.
The chemical composition and the major use of the minerals are given below and in the
following table :

Ti minerals: The ilmenite, rutile and the leucoxene are used in the for making titanium
dioxide powder for the pigment industry. This also can be used in the paper and tyre
manufacturing. Titanium metal can be used in the biomedical implants, aero frames in space
industry and shipbuilding.
Zircon: It is used in the foundries, refractories, ceramics and chemical industries. It is an
important material for structural ceramics and its purest form is formed the "American
diamond"
Sillimanite: Used in the refractory industry
Garnet: Garnet is having a family of six minerals, out of which the Almandine garnet (Iron
Aluminium orthosilicate) is only suitable to the abrasive industry. It occurs in variety of mesh

sizes ranging from coarse, medium and fine. It has a hardness of 7 to 8 in Mohs scale. It
retains its crystal structure eve after recycled twice or thrice. The other members of the garnet
family break down under high-pressure hence they are not suitable to the abrasive industry.
It is used abrasive blasting, water jet cutting, water filtration, Manufacturing of coated
abrasives, grinding and lapping of glass, metals, ceramics and plastics.
Major non-technical uses of garnet are in sand blasting and abrasive jet cutting. Garnet has an
advantage of containing essentially no crystalline (free) silica and hence does not cause
silicosis in its industrial application. Also Almandine garnet contains no leach able metals. It
has high specific gravity than quartz so when used in sand blasting or water jet cutting garnet
makes 3 or 4 time more impact than quartz grains of the same size.
In abrasive jet cutting, which is more prevalent in N America and Europe almandine, garnet
grains of 0.18mm size are usually entrained in a stream of high velocity water which
impinges on the material to be cut at a pressure of 5.5 X 10 +8 Pa. Abrasive jet cutting is
used to shape cut marbles, granites, high strength steel bridges decking aerospace composites
automotive glass.
Beach placers:
The Scenario Worldwide and Indian Scenario:
These beach placers are occurring all along the coastlines in the world. However, USA, South
Africa, Australia, Japan, China, Sri Lanka and India are the chief producers of these minerals.
Out of these, Australia, South Africa and India are the chief producers of all the eight
minerals mentioned in the list above.
If we consider resource position of the Heavy minerals, South Africa, Australia and India,
these countries are having good deposits but as on date, Australia and South Africa are the
chief exporters of these minerals to the world. If we analyze the deposits of the world they are
fast dwindling and the grade of the deposits is inferior to the Indian deposits. In the world 3%
grade of the heavy minerals is the cut off, and in India we are having 10 % grade in our
deposits. But we are not exploiting. Only one Government under taking agency that is Indian
Rare Earths Limited located at Chatrapur, Orissa and one at Kerala is exploiting these
minerals.
As the world deposits are fast depleting, and on shore mining has many environmental and
social problems the offshore coastal deposits are gaining importance in the international
arena.
At present mining in going on in onshore coastal sands with the help of surface open cast
methods which use excavators and tippers

Present Methods of mining and minerals separation on the coast: Two types of mining process are involved in the on shore beach placers mining. 1) Dry mining to win the mineral up to the water table depth and the wet mining to win the minerals below the water table. In dry process dozers, wheel loaders, shovels etc are used. This material is transported thorough pipes or tippers to pre concentration plant. And there the spirals are used. In the concentrator, separation is achieved by number of stages like rougher, cleaner, reclaimed and scavenger. The moisture from the concentrate is taken out from hydro cyclones or by allowing it to be drained on the land. This concentrate contains 10% of heavy minerals. In the Mineral Separation Plant the fallowing machinery is used.
1) Mineral processing - High-tension separator, electrostatic separators electromagnetic separators, wet tables, air tables, flotation cells and vibratory screens etc.
2) Material handling equipment - Belt conveyors, bucket elevators, screw conveyors and slurry pumps.
3) Heating and drying - rotary driers, fluidized bed driers, shaft dryers.
4)The sand is pre heated to 130 degrees as a part of process requirement in the high-tension separation in which ilmenite and rutile are taken as conducting minerals and zircon, sillimanite garnet and monazite as non-conducting minerals.
5) Magnetic separators are used to separate the magnetic ilmenite from non-magnetic rutile product and monazite garnet and but paramagnetic minerals are removed from non-magnetic zircon.
6) Sillimanite concentrator is taken as float in the flotation and is further cleaned by high-tension magnetic separators. Monazite is taken at air tables. Except monazite all the minerals are kept in bags and the monazite in the containers. The typical flow sheet is given below.
OBJECT OF THE INVENTION:-
It is a principal object of the invention to introduce an improved and enhanced method and
technology for effective separation, extraction, filtration of heterogenic mineral compositions
from coastal sand which is dredged in vast quantities.
It is furthermore a principal of the invention to provide an improved way and methodology
for effective utilization of the coastal sands and enhance the potential of extraction to the
maximum level possible of the rare earth minerals contained in these coastal sands.
It is yet another object of the invention to maximize the output of exploration of coastal sands
of the country, and increasing the number of heavy minerals obtained by filtration and

extraction of coastal sands, when compared to the miniscule number of heavy minerals
achieved by currently employed methods.
It is a principle object of the invention that through the process which might appear to be
similar to on shore mining but different in method of mining and pants or floating decks that
float over sea, which have pre concentration and separation plants installed on it.
Further, to be Precise, the dredges (of various types based on the mineral deposit characters)
and then pre concentration of the dredges is done with the help of spirals and then magnetic
and electrostatic and electromagnetic separators of various capacities
DESCRIPTION OF THE INVENTION:-
Heavy minerals are those compounds which have greater Specific gravities (relative density) which are in the range of greater than 2.89. These heavy minerals are generally found to be occurring on the sea coast. They can be observed to be deposited up to a distance of 1 or 2 kilometres from the coastal area towards seawards side. It has been clearly established that in India, not a great deal of mining and extraction of heavy minerals, as per the studies conducted and scientific reports on sea bed resources estimation. National Institute of Oceanography (NIO) Goa, has conducted studies and estimated the existence of polymetallic nodules in the sea bed on the territorial waters of India.
It has been studied that in the Indian sea coast, that in very close proximity to the coast and then upto first 1 km in seawards direction, there occurs heavy minerals mixed in the coastal sand which can be extracted and utilized commercially as they are classified as strategic minerals.
It has been even found out that micro diamonds and xenotime, which is a radioactive mineral are found in the stretch between Narsapur and Avanigadda coastal areas in the Bay of Bengal in Andhra Pradesh. These minerals have been found to occur in the offshore areas of this coastal stretch.
The extraction process of the heavy mineral sands first involves in Dredging of the sands by utilizing various types of Dredges.

Further, upon dredging the sands obtained are cleaned and the preliminary deposits of heavy
minerals are separated from the raw sand by appropriate utilization of spirals which are the
primary and preliminary concentrators. The passing of sands through spirals utilizing gravity
separation and other methods are suitably employed. Later, the heavy minerals are separated
using sieves, magnetic as well as electromagnetic separation methods.
Magnetic Separation :-
Magnetic separation is a process in which magnetically susceptible material is extracted from
a mixture using a magnetic force. This separation technique can be useful in mining materials
with ferrous content contained in them as it is attracted to a magnet.
Electromagnetic separation :-
Separation of minerals utilizing differences in their electrical properties is carried out using
electromagnetic separation process. Especially heavy minerals like Rutile can be extracted by
employing Electromagnetic separation.
Thus, it can be seen that by employing of appropriate technology right from dredging, mining and separation, filtration and extraction of coastal sands, the optimal levels of heavy minerals extracted from the coastal sands of our country can be enhanced and thus it can contribute more productively to the Economy and give much revenue to the Exchequer of the Nation. The precious wealth of coastal sand, which is now being wasted after dredging as just few of the minerals are extracted and thus rendering the coastal sands worth several crores of rupees of practically less or no value.
The types of dredgers used are
I) Bucket wheel and
II) Cutter suction.
In the bucket wheel type of dredge the bucket wheel is in similar in shape to bucket wheel excavator used for large open cast mining. Cutter suction unit is equipped with hydraulic jets to loosen and agitate the sand prior to drawing it towards the suction pipeline through which the slurry along with other mineral sand material moves. The slurry is pumped to a trammel screen to remove the oversized materials like pebbles and roots, trash etc. The oversized material is discharged into the sea. The under sized material is collected in a head bin. This also acts as surge bin.

The dredger capacities vary from 100 to 500 tph and depend on the mining plan. The dredging depth is around 1 to 100m and it may vary with distribution of mineral deposit in the area. The pulp density of sand dredged is around 15 to 20%. The dredge has a suction diameter of 450mm with a 525-kW/3.3kV motor for the dredge pump. The dredge movement is controlled by winches. The winches and the cutter ladder are hydraulically operated. In the wet concentrator separation of heavy minerals and lighter gangue minerals is achieved by exploiting the difference in the density and size between the heavy and the light minerals.
The spirals are mounted on an integrated pontoon along which the dredger on the sea. The dredge moves forward mines the sand and the tailings from the spirals concentrators are pumped towards rear side of the dredge into the sea.
The wet concentrator output is (90% heavies) is fed to a concentrator up gradation plant (CUP) where the percentage of heavy minerals is upgraded to around 77% In this plant the light heavy minerals garnet, sillimanite are taken out from the spirals as middling/tailings and are separately stockpiled. Efforts are on to recover the minerals by using the wet high intensity magnetic separator/wet tables. The concentrate from the CUP is fed to the minerals separation plant for further separation.
The process is though similar to the process used on the on shore, scores an edge over the other processes, for the following reasons:-
i) It is Environmental friendly, not creating any kind of socio economic problems
ii) It depends on availability of resources in offshore coastal regions which are untapped
hitherto iii) This process is aimed at tapping the zones for future metals and mining zones which
the applicant wants to use at the earliest and get benefits of the untapped mineral
wealth. iv) In this process it can be seen that the inputs can be raised and can mine seasonally or
continuously as the resource is replenishable. Further, entire activity is taken place
on the floating decks. The difference in operations is given below as per the table.

CLAIMS -
What is claimed is
1) A process for extraction of heavy minerals and rare earth minerals and their subsequent filtration from coastal sands, essentially comprising of the processes of dredging, mining and separation, filtration and extraction of coastal sands, for obtaining optimal levels of heavy minerals extracted from the said coastal sands
2) The process of extraction as claimed in claim 1, comprises of dredgers, of the types of

(a) Bucket wheel and
(b) Cutter suction.
wherein the bucket wheel type of dredge the bucket wheel is in the shape of bucket wheel excavator, and the said Cutter suction unit is equipped with hydraulic jets to loosen and agitate the sand prior to drawing it towards the suction pipeline through which the slurry along with other mineral sand material moves and the slurry is pumped to a trammel screen to remove the oversized materials like pebbles and roots, trash etc. The oversized material is discharged into the sea. The under sized material is collected in a head bin known as surge bin.
3) The capacities of the said dredger as claimed in claim 2, the capacities vary in the range of 100 to 500 tph and depend on the mining plan and the dredging depth is in the range of 1 to 100m and is varying with distribution of mineral deposit in the area, the pulp density of sand dredged is in the range of 15 to 20%.
4) The said dredge as claimed in claim 2 has a suction diameter of 450mm with a 525-kW/3.3kV motor for the dredge pump, the dredge movement is controlled by winches, the said winches and the said cutter ladders are operable hydraulically and the wet concentrator separation of heavy minerals and lighter gangue minerals is

achieved by exploiting the difference in the density and size between the heavy and the light minerals
5) A method for extraction of heavy minerals from coastal sands, wherein the primary concentration is the desired output is enabled by spirals and then sieving by dry sieving techniques, further upon, the separated products will be further separated into individual minerals using magnetic, electromagnetic, air flotation tablesand all the related equipments are on a floating platform close to dredge floating on the sea surface.
6) The method for extraction of heavy minerals from coastal sands, as claimed in claim 5, wherein the wastes generated will be transported through pipes using natural gravity without requirement for pumping etc.
7) The method for extraction of heavy and rare earth minerals from coastal sands as claimed in claim 5, wherein the said method is friendly to the Environment, and not capable of creating any kind of socio economic problems to the society.
8) The method for extraction of heavy and rare earth minerals from coastal sands as claimed in claim 5, wherein the method depends on availability of resources in the offshore coastal regions which are untapped hitherto and the said method is aimed at tapping the zones of location of futuristic exploration of metals and their respective mining zones
9) The method for extraction of heavy and rare earth minerals from coastal sands as claimed in claim 5, wherein the output is clear and capable of extracting of minerals in high concentration eliminating the slags / impurities from the said output
10) A process and method for extraction of heavy and rare earth minerals from coastal sands substantially referred herein above with respect to the descriptions and accompanied technology with the flow diagrams.