System and method thereof for off shore mining

A system and method of off shore mining for retrieval and extraction of heavy mineral concentrate from placer deposits or other suitable materials. The system comprises a dredge vessel and a barge, coupled in conjunction to the dredge vessel. The dredge vessel having thereon a dredging unit, at least one gravity separator and spiral separators for procurement of total heavy minerals from dredged sediment and debris. The barge is configured to acquire and process the total heavy minerals, wherein the barge has thereon at least one magnetic separator, electro-magnetic separators, and density separators for separation of desired minerals based on their physical properties. The system further comprises at least one discharge conduit for tailing of wastes, leftover after extraction and separation of desired minerals, back into water bodies.

BACKGROUND

1. Field of the Disclosure

The present disclosure generally relates to the field of deep sea mining. Particularly, but not exclusively, the present disclosure relates to a system and method of off shore mining for retrieval and extraction of heavy mineral concentrate from placer deposits or other suitable materials.

2. Discussion of the Background Art

Advancement in technology and rapidly progressing industrialization in the current modern world has spurred an upsurge in usage of minerals and metals. Increasing world demand for minerals mandates requisite of new sources of high-quality reserves of heavy minerals concentrate (HMC) which contains metals, minerals and precious stones including gold, diamond, magnetite, rutile, ilmenite, zircon and like. HMC is currently being dredged from continental shelves of global sea floor having placer deposits to cater the increasing world demand for minerals. Placer deposit is a natural concentration of heavy minerals caused by the effect of gravity and weathering processes. Thus, the heavy minerals become concentrated in stream, beach, and lag (residual) gravels and constitute workable ore deposits.

The continental shelves being dredged may constitutes only a very small fraction of HMC from the material recovered from the sea-bed. In generally, the material recovered from the sea-bed is transport to an on-shore processing plant for retrieval and extraction of HMC from the material recovered from the sea-bed. This method is considerably very uneconomical due to increase in cost arising from supply and maintenance of mining and transportation equipment. Moreover, in on shore processing plant, large volumes of wastes like sand, gravel and silt are separated after retrieval and extraction of HMC. With the increasing environmental and pollutions control norms, disposal of these wastes is stipulated and screened to minimize disruption of landscapes, this in turn add a significant cost for the operation. Conventionally, various off-shore techniques have been proposed in order to obtain HMC by undertaking primary separation of material recovered from the sea-bed, considering the fact that waste disposal may be easier and therefore cheaper than on land. Although greater care must be exercised to ensure that waste is not deposited on unworked reserves on the sea-bed. Furthermore, these conventional techniques don't provide a system and method which accomplishes the complete retrieval and extraction of heavy mineral concentrate from material recovered from the sea-bed. The conventional off-shore techniques have limitation with respect to production capacities, higher production costs. Also, there is no significant cost difference in comparative cost between on-shore and off-shore techniques except in special circumstances such as distance from a shore base, environmental factors and like.

The present disclosure is directed to mitigate the above stated problems or other similar problems associated with the prior art.

SUMMARY

One or more shortcomings of the existing methods is overcome by a system and method thereof for off shore mining as claimed in the present disclosure.

Additional features and advantages are realized through the techniques of the present disclosure. Other embodiments and aspects of the disclosure are described in detail herein and are considered a part of the claimed disclosure.

In a non-limiting embodiment of the present disclosure, an off-shore mining system comprises a dredge vessel and a barge. The dredge vessel having thereon a dredging unit adapted for excavate of water bodies and procurement of sediment and debris, at least one gravity separator adapted for separation and exclusion of oversized particles from sediments and debris. Further the dredge vessel comprises of at least one spiral classifier coupled to at least one gravity separator wherein at least one spiral classifier is configured to receive finer particles of sediments and debris to extract total heavy minerals and at least one discharge conduit for tailing of wastes, leftover after extracting total heavy minerals, back into water bodies. The barge is operably coupled in conjunction to the dredge vessel, configured to acquire and process the total heavy minerals, wherein the barge has thereon a dewatering unit configured to expel water absorbed by the total heavy minerals, at least one magnetic separator for separation of desired minerals from total heavy minerals based on magnetic properties of the minerals, at least one electro-magnetic separator for separation of desired minerals from total heavy minerals based on electro-magnetic properties of the minerals and at least one density separator for further separation of desired mineral from total heavy minerals based on density of minerals. Furthermore, the barge comprises of at least one discharge conduit for tailing of wastes, leftover after extraction and separation of desired minerals, back into water bodies.

In another non-limiting embodiment of the present disclosure, a method for off shore mining comprising the steps of dredging and procuring sediments and debris from water bodies, excluding oversized particles and obtaining of finer particles from sediments and debris by gravity separators, extracting total heavy minerals from finer particles of sediments and debris by spiral classifiers. The method further comprises the steps of dewatering the total heavy minerals to expel water absorbed by the total heavy minerals and separation of desired minerals from total heavy minerals based on at least one predetermined properties selected from a group comprising magnetic properties, electro-magnetic properties, and density. Furthermore, the method comprises the step of tailing of wastes, leftover after extraction and separation of desired minerals, back into water bodies.

It is to be understood that the aspects and embodiments of the disclosure described above may be used in any combination with each other. Several of the aspects and embodiments may be combined together to form a further embodiment of the disclosure.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Embodiments of the present disclosure are related to an off shore mining system (100).FIG. 1illustrates a block diagram of off shore mining system (100). The dredge vessel (10) having thereon a dredging unit (11), at least one gravity separator (12), and at least one spiral classifiers (13).

The dredging unit (11) is adapted to perform excavation of a bed or body of water bodies (lakes, rivers, harbours, and like) for procurement of sediment and debris. The dredging unit (11) is substantially a mechanical dredger or a hydraulic dredger or a hydrodynamic dredger, such as a bucket wheel dredger, cutter suction dredger and like. The bucket wheel dredger, employs a plurality of buckets on a revolving chain to dig, scope and remove large quantities of sediment and debris from the bed of water bodies below a plane of movement of the bucket wheel dredger. The cutter suction dredger is equipped with a rotating cutter head, which can cut hard soil or rock, existing in the bed of the water bodies, into fragments. The cutter head is a rotating mechanical device, mounted in front of the suction head and rotating along the axis of the suction pipe. The fragment of sediment and debris thus produced is then sucked in by dredge pumps. Cutter suction dredger can be configured cut the soil according to a pre-set profile.

The gravity separators (12) are coupled to the dredging unit (11), wherein the gravity separators (12) are adapted for separation and exclusion of oversized particles from sediments and debris obtained by the dredging unit (11). The gravity separator (12) is operate by the principle of separation based in difference in size and shape of the particles of sediments and debris. Thus, a finer particle of sediments and debris are obtained by gravity separation (12) of the sediments and debris obtained by the dredging unit (11). The gravity separator (12) is substantially a vibrating screen or a rotary sieve and like.

The spiral classifier (13) is coupled to at least one gravity separator (12), wherein the spiral classifier (13) are configured to receive finer particles of sediment and debris to obtained total heavy minerals. The spiral classifier (13) segregate total heavy minerals and lightweight waste particles, such as sand and silt, from the finer particles of sediment and debris. The segregation is based on the datum that the waste particles have comparatively less specific gravity in comparison with specific gravity of the total heavy minerals. The spiral classifier (13) receive the finer particles of sediment and debris and pass them through a spiral. As the particles of sediment and debris travels down the spiral, the total heavy minerals are segregated from the waste particles.

The dredge vessel (10) further comprises of at least one discharge conduit (14) coupled to at least one spiral classifier (13) for tailing of wastes, leftover after extracting total heavy minerals, back into water bodies.

The barge (20) is a floating vessel which is operably coupled in conjunction accompanying the dredge vessel (10). The barge (20) is configured to acquire and process the total heavy minerals obtained by the dredge vessel (10). The barge (20) has thereon a dewatering unit (21), at least one magnetic separator (22), at least one electro-magnetic separator (23), and at least one density separator (24). The dewatering unit (21) is configured to expel water absorbed by the total heavy mineral. The dewatering unit (21) can accomplish removal of water from the total heavy minerals by sun drying or application of ovens and other similar heating or dehydrating equipment. The magnetic separator (22) is an equipment for selectively retaining magnetic materials, so as to separate them from material fed into the equipment. The magnetic separator (22) is employed for separation of desired minerals from total heavy minerals based on magnetic properties of the minerals. Similarly, the electro-magnetic separator (23) is an equipment for selectively retaining electro-magnetic materials, so as to separate them from material fed into the equipment. The electro-magnetic separator (23) is employed for separation of desired minerals from total heavy minerals based on electrical properties of the minerals. The density separator (24) is a device to classify, separate or sort particles in a fluid (air or water) suspension based on the ratio of their centripetal force to fluid resistance. The density separators (24) are substantially a hydro-sizer or a cyclonic separator or an air/liquid density separator and like.

The barge (20) further includes at least one discharge conduit (25) for tailing of wastes, leftover after extraction and separation of desired minerals, back into water bodies.

In an embodiment, the dewatering unit (21), magnetic separators (22), electro-magnetic separators (23), and density separators (24) included in the barge (20) can be arranged and configured in any sequence based on the requirement of user.

In an embodiment, the off shore mining system (100) further comprises of at least one intermediate conduit (30) interconnecting said dredge vessel (10) with the barge (20) for transferring the total heavy minerals by pumps.

In an embodiment, the total heavy minerals can be passed multiple times through the magnetic separators (22), electro-magnetic separators (23), and density separators (24) to achieve complete extraction of desired minerals.

In an embodiment, a method for off shore mining comprising the steps of:1. dredging and procurement of sediments and debris from water bodies,2. exclusion of oversized particles and obtaining of finer particles from sediments and debris by gravity separators,3. extracting total heavy minerals from finer particles of sediments and debris by spiral classifiers,4. dewatering of total heavy minerals to expel water absorbed by the total heavy minerals,5. separation of desired minerals from total heavy minerals based on at least one predetermined properties selected from a group comprising magnetic properties, electro-magnetic properties, density and like, and6. tailing of wastes, leftover after extraction and separation of desired minerals, back into water bodies.

EQUIVALENTS

List of reference numerals:Reference NumeralParticular10010Dredge vessel11Dredging unit12At least one gravity separator13At least one spiral classifier14At least one discharge conduit20Barge21Dewatering unit22At least one magnetic separator23At least one electro-magnetic separator24At least one density separator25At least one discharge conduit30At least one Intermediate conduit