University of Mines and Technology (UMaT),
Tarkwa, Ghana
BSc MININING ENGINEERING
MN 274
Alluvial and
Ocean Mining
CHAPTER 1
Introduction to Alluvial Mining
Lecturer
Dr Clara Akalanya Abuntori
2024 1
Course Objectives
To outline the processes
To present the basics of involved in mining alluvial
alluvial and ocean mining deposits and mining in the
ocean.
2
Course Presentation
❑The course will be delivered through
✓VLE/Zoom
✓Practical sessions
✓Course is taught through lectures supported with handouts
❑The student can best understand and appreciate the subject by
attending all lectures and tutorials, by reading references and
hand-outs, and by completing all assignments and course work
on schedule.
3
Assessment
❑Tutorials will be in the form of problem solving.
❑Assignments and Tests
❑Course work will require that each group of students will be assigned to
study a specific problem.
❑Final examination
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Assessment
The final subject mark will comprise the following:
❑Continuous Assessment (40%) made up of:
✓Attendance 10%
✓Course work (Mini-project), assignments and Tests 30%
❑Final Examination 60%
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Definition
❑The word alluvial is derived from a Latin word aluvius from alluere “to
wash against”
❑Alluvial mining takes its origin from placer mining
✓Placer mining is the process of separating heavily eroded minerals such as
diamonds, gold from sand or gravel
❑Spanish origin meaning to please or pleasure because it is an easy form of
mining.
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History
❑Alluvial mining practiced by ancient Romans and Spanish at about 25BC.
❑Hydraulic mining methods such as hushing were used during these ancient times for
gold extraction.
❑Notable gold rush in North America:
✓ The California gold rush (from 1848 to 1855)
✓ Colorado gold rush (1858 until the creation of the Colorado territory)
✓ The Fruser Canyon gold rush which was discovered on the Thompson river in 1855)
✓ The Klondike gold rush ( 1896-1899)
✓ Deposits of gold were found on shores of Gulf of Guinea by the Europeans in the 15th century
(1401-1500) hence the name Gold Coast.
✓ The recent Chinese influx into the small scale alluvial mining symbolises a gold rush.
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Process of Formation
❑Alluvial deposits are formed by the natural concentration of weathered
products of rock bearing minerals
❑They are unconsolidated sediments that have been deposited by running
water.
❑In geology; alluvial deposit is an accumulation of valuable minerals formed
by gravity separation during sedimentation processes.
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Process of Formation
In general, the following factors influence the formation of alluvial deposits:
❑The rate of weathering;
❑The disintegration of mineral bearing rock;
❑The amount of rainfall;
❑The relief or topography;
❑The conditions under which the eroded sand, gravel and pebbles settle or are
deposited.
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Types of Alluvial Deposits
❑Residual or Eluvial deposits: occurs above the source rock
❑Hillside Slope Placer/ Colluvium: occurs at the base of hillslopes
❑Stream or Fluvial deposits: transported and deposited by rivers
❑Pluvial:
❑Dry or Bajada Placers: fan shaped deposits formed by deposition of sediments within a
stream onto a flat land at the base of a mountain
❑Eolian or Wind formed Placers
❑Glacier deposits
❑Beach Placers
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Characteristics
❑They are heavy
❑They are stable
❑They are fertile
❑Resistance to mechanical wear
❑They are of transported origin
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