alluvial mining

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Alluvial MiningA presentation by

Arkaprabha Sarkar

M.Sc (P) Applied Geology

Kurukshetra University

Kurukshetra

Under the guidance of

Ms. Sarita Mann

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What is Alluvial Mining?

Alluvial mining or Placer miningis the

procedure of extracting ore minerals from

placer deposits formed by exogenic

geomorphic processes.

Alluvial mining considered as a special case of

open cast mining and quarrying

MISCONCEPTION!!!

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Placer Deposits

Placer deposits are sedimentary ore deposits ofheavy ore minerals formed by mechanicalconcentration of minerals in sediments deposited

due earth surface processes.

Can be of the following types:- Eluvial placers

- Alluvial placers- Beach placers- Aeolian placers

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A recent deposit

Age: Less than 20ka

Lithology: Very low degree of compaction. Composed of loose sand

Site: Ropar, Punjab

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An old placer deposit

Age: Precambriam

Lithology: Lithified sediments

Site: South Africa

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Process of mining a placer

Open Cast Methods

Used in recently developed

placer mines

Generally deposits are notlithified

Underground methods

Used in deep seated old

placer mines

Usually deposits areconsolidated

NOTE:

The choice of methods is decided on the basis of the following criteria:

Study of lithological characters

Simulation of efficiency of various methods on the current scenario

Simulation of modifications on existing methods for the particular scenario

Labour cost and capital investments

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ALLUVIAL MINING METHODS

Methods of mining are explainedtaking the reference of *Tin mining

industry of Malaysia

*Mining of tin from placers in Malaysia was started in 1820 by the Chinese settlers.

The industry continued to hold the economy of Malaysia along with the rubber

industry until 1995 when the mines were shutdown. The mines were shutdown

due to exhaustion of resources.

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Panning

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Rocker Box

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Long Tom

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Sluice Boxes

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Hydraulicking

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Dredging

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Dredge machine working in an open cast alluvial mine


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Underground Method

Favona Gold Mines, New Zealand

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Alluvial mines in India

Ilmenite-Monazite-Rutile mining in Kerala

coast

Chavakkad-Ponnani gold mines in beach

placers of Kerala

Gold mines in alluvial placers of Ghaggar

(mining has been stopped now)

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EFFICIENCY OF MINING METHODS

Based on the production of tin in Malaysia over the entire period,

efficiency of the various methods used is estimated statistically.

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Production of tin over the years

Year Dredge %

Gravel

%

Open

%

Under-

%

Dulang

% Others % TotalPump Cast ground Washing

1970 23,931 32.4 40,739 55.2 2,504 3.4 2,254 3.1 2,828 3.8 1,539 2.1 73,795

1975 20,329 31.6 35,183 54.7 2,535 3.9 1,894 2.9 3,081 4.8 1,342 2.1 64,364

1980 18,222 29.7 34,484 56.2 2,705 4.4 1,085 1.8 3,246 5.3 1,662 2.7 61,404

1989 11,963 37.3 13,263 41.4 2,905 9.1 103 0.3 2,835 8.8 965 3.0 32,034

1990 10,267 36.1 12,216 42.9 2,173 7.6 102 0.4 2,601 9.1 1,109 3.9 28,468

1991 9,515 45.9 6,476 31.3 1,754 8.5 71 0.3 2,065 10.0 829 4.0 20,710

1992 6,072 42.3 3,886 27.1 1,592 11.1 71 0.5 1,640 11.4 1,078 7.5 14,339

1993 3,522 33.9 3,426 33.0 1,653 15.9 48 0.5 1,059 10.2 676 6.5 10,384

1994 1,355 21 2,438 37.8 1,375 21.3 72 1.1 721 11.2 497 7.7 6,458

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Production of tin by various methods

0

5000

10000

15000

20000

25000

30000

35000

40000

45000

1970 1975 1980 1989 1990 1991 1992 1993 1994

Chart Title

Dredge

Gravel pump

Open Cast

Underground

Dulang Washing

Others

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Netproduction

Years


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Efficiency of various methods

0

10

20

30

40

50

60

1970 1975 1980 1989 1990 1991 1992 1993 1994

AxisTitle

Percentage yield of the methods used over the years

Dredge

Gravel pump

Open Cast

Underground

Dulang Washing

Others

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Percentage

yield

Years


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Conclusion

Alluvial mining is done in sedimentary

deposits. Mining methods are chosen on the

basis of the lithological characteristics of the

deposits.

Grade of deposit is generally low, hence, all

methods are comparatively less expensive.

Mining projects involving alluvial mining have

generally low capital investments.

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References

Mining Geology by R.N.P Arogyaswamy

Ore geology and Industrial Minerals: An

Introduction by Anthony M. Evans

www1.american.edu

Google Images

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Thank You

Feel free to clear your doubts!

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