Dredging and beneficiation of sandstones

Dredging improves sand mining operation

As demand for high quality silica sand increased in important glass manufacturing, there is need to accelerate its continuing programmed of modernization and expansion of production facilities.

A thorough engineering examination and evaluation indicated that a modern high capacity dredger could be used to best advantage in one portion of the extensive mining operation.

The 3-in-1 benefits of dredging (mining), transportation and filling could be obtained by operating one modern hydraulic pipeline cutter head dredger in this particular sector. This could represent a marked improvement over the previous operation which required several low powered dredgers to work in the same pit on an around – the – clock basis in order to meet their portion of the plants daily requirements.

The job for heavy equipment which could:

(1)     Transport material over extended pipelines as the size of the pit increases.

(2)     Provide capacities which could permit an 8 hours operation.

 The dredger

The term dredger is used to describe the housing in which the dredging operation is carried out. It consists of the operator’s cabin and other components. The dredger is a floating vessel.

The various components are listed below:

(1)     The submersible pump

(2)     The boom

(3)     The draw works

(4)     Segment Pipelines

 The submersible pump

The pump is a submersible one of operating at a depth of 15m would mine material from the average of 12m below water level. The cutter head would dig into the clay and sand agglomerate.

The pump is a toyo heavy duty centrifugal suction type with 200mm bore discharge driven electrically. The characteristics of material to be dredged calls for a simple pump design that would withstand the exceeding abrasive nature of the crude quartzite sand. It is constructed with a case of abrasion resistant special nickel alloy cast iron. The output of dredger depends on the type of soil.

The boom

The boom consists of a uniform bar length 17m which is hinged at the side of the dredger. It is attached at the other end to the pump. It functions with the aid of sling wires operated from a winch for lowering and raising the pump during dredging operation and when pump requires minor repair.

The sling wire is attached to the eye of the pump. The boom helps to determine the depth of operation.

Draw works

The draw comprises of the winch, pulley system and lines. The energy needed is supplied electrically by a motor and gear system. The sling – wire passes through the pulleys. The moveable pulley submerges with the pump and boom on lowering while the fixed pulley passes through a prop via the sling wire. The draw work is the core of the dredging process.

Lines are attached to the side of the dredger and fixed at specific locations of the mine – pit for relocating the dredger at various positions in the mine pit.

 Segment pipelines

It is used in transporting dredged material to the storage silo for subsequent processing. Flexible hose are used in areas that need flexibility.

The pipelines are in different segment 6.5m in length, 30cm in diameter and 2.5cm thickness. It has flanges at both sides. It is mounted on two beams attached to floating pipes at two different intervals with manholes at the middle to help discharge material in case of blockage.

 Dredging operation

The process of dredging requires specialized hands owning to the sensitive nature of job. The operation begins by lowering the pump and simultaneously putting in the pump followed by side-by-side monitoring of the pressure gauge.

Dredging is usually carried out at a maximum of 3 bars and a minimum of 2.5 bars. The operation consists of lowering the pump to dredge reasonable quality of sand and raising it to flush at reasonable intervals to prevent blockage of segment pipes. The place where experience comes in is the monitoring of the storage silo outlet and the level of water at the side of the segment pipelines as a result of possible failure of gauge. The outlet is monitored to know the quality of material falling off the outlet and the pipelines to know the weight or capacity of sand being dredged so as to prevent overloading of pipelines and subsequent blockage.

Caving is the only serious problem in dredging which occurs as undredged areas collapses on the submissible pump and if not attended to urgently may lead to blockage due to excessive dredging of material.

Unique method of storage

The sand and water mixture is pumped into the storage “silo A”. This plan proves itself in execution with toyo pump forming the nucleus of mining operation.

The pump not only enables us to work in a shift but it possible to do in 8hrs.

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Gupta stone
Gupta stone
1 year ago

Thanks for sharing useful content.
Gupta Stone is into export of natural stone field and offer a wide variety of stones to suit present day market trends.

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