1. Daniel Limpitlaw 6th CASM Meeting Antsirabe, 10-15 November, 2006
Engineering for Small Scale Mining and Sustainable Livelihoods in Africa
Daniel Limpitlaw
6th CASM Meeting
Antsirabe, November, 2006
Specialists in mineral and metallurgical technology 1

2. Sustainability Theory
Sustainable Livelihoods
Impacts on sustainability by ASM
Natural capital
Social capital
Human capital
Financial capital
Physical capital 2

3. This presentation provides some examples of the sustainable development (SD) dividend that can be extracted by applying appropriate mining engineering approaches to ASM operations 3

4. Improving Mining Methods to Optimise the Contribution of ASM to Sustainability
organisation, productivity and production of operations,
quality and constancy of production,
value-adding sorting, washing and/or processing,
healthy and safe mining conditions, and
rehabilitation to remove environmental degradation.
improving the organisation, productivity and production of operations,
ensuring quality and constancy of production and supply to consumers,
encouraging value-adding sorting, washing and/or processing, as appropriate and feasible,
improved working conditions – the promotion of healthy and safe mining conditions with avoidance of mine site collapses, and
improving environmental management practices at mine sites – rehabilitation to remove environmental degradation caused by the mining and the danger 4

5. SHALLOW UNDERGROUND MINING IN NAFADA
Presented by kind permission of the
Ministry of Solid Minerals Development
of The Federal Republic of Nigeria 5

6. SHALLOW UNDERGROUND MINING IN NAFADA
Photo: N. Baartjes, Mintek, 2005
Photo: N. Baartjes, Mintek, 2005
A typical mine shaft from a gypsum mine site located near Baruwo Wendi. The mineworkers feet are placed on the contact between overburden and top of the Fika Shale about 4m below shaft collar
Mineworker at the Fika Gypsum Field showing the typical mining implements used by the gypsum miners
A typical mine shaft from a gypsum mine site, near Baruwo Wendi.
Mineworker at the Fika Gypsum Field 6

7. Modified Loto Mining System
Shafts sunk through overburden
Ore horizon 5 m below surface
tunnels are driven out to intersect the shaft bottom of the neighbouring shaft (20 to 30 m away)
five workers at each shaft (two miners working underground, a miner hoisting material to surface using a rope and bucket, and two sorters) Approximately 14,000 people are involved in the production of 45,000 t of gypsum annually 7

8. Surface impacts of shaft-type ASM activities8

9. Surface impacts of shaft-type ASM activities9

10. A more sustainable approach
- based on a report to Mintek by Limpitlaw & Lind, 2005 10

11. Nafada Fika Overburden 5 m 10 m 4 m Orebody 2 m Footwall11
Geological section

12. Nafada
Fika
Overburden
5 m
10 m
4 m
2 m
Footwall
Orebody pillar
remnants
after the modified Loto mining

13. General layout of proposed strip mining method
Direction
of mining
Overburden
Spoil Piles
Mined
out area
Strip

14. Overburden pre-mining14
plan view – pre mining

15. Length as long as orebody extent Overburden removed to top of orebody
7 m/hr
Strip 1 –
Length as long as orebody extent
Overburden removed to top of orebody
Excavator
Operation of excavator
Spoil pile of waste overburden 15
plan view – box cut

16. Excavator removes overburden in a strip To expose the top of orebody
Overburden spoil
pile
Excavator removes overburden in a strip
To expose the top of orebody
Overburden
4 m
Orebody
Footwall 16
section – stripping of first cut

17. Ore extracted by manual means to basement contact
Removed from ‘pit’ and sorted on surface
3 m
1 m wide safety buffer adjacent to highwall
Waste from sorting returned to spoil pile
Spoil pile
Excavator continues removing overburden
ahead of ore extraction process 17
plan view – completion of first strip

18. Ore extracted from strip to basement
Overburden spoil pile
Waste from ore
sorting returned to
Waste stockpile
Ore extracted from strip to basement
1 m wide safety buffer adjacent to highwall
4 m
Overburden
3 m
Orebody
Footwall 18
section – ore mining commences

19. Excavator begins extracting overburden in Strip 2 adjacent to Strip 1
Spoil pile
Sorted waste returned to stockpile
1 m wide safety buffer adjacent to highwall
Ramp access out of pit for
ore to be sorted on surface 19
plan view – ore mining progresses

20. Excavator removes overburden in a strip
To expose the top of orebody for Strip 2
Overburden spoil
Pile from strip 1
3 m
4 m
Overburden spoil
Pile from strip 2 placed in
Mined out strip zone
1 m
Footwall
Direction of overall mining 20
section – 2nd strip commences

21. Loto System (proposed production)
Loto System (current production)
Loto System (proposed production)
Modified Strip Mining
Production target
45,000t
80,000 t
No. of Loto shafts required
2,800
5,000 -
Mining area disturbed per mining season
2.25 km2
4.5 km2
0.066 km2 (pit)
0.19 km2 (pit, o/burden and prestrip)
Mining workforce
14,000
25,000
15,000
Nature of post mining surface
Dangerous shafts, potential for future subsidence
Recontoured, revegetated and stabilised. Potential for future agricultural use
Potential ore extraction
25%
Up to 100%