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, 10-15 November, 2006 Specialists in mineral and metallurgical technology 1

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

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

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

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

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

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

Surface impacts of shaft-type ASM activities 8

Surface impacts of shaft-type ASM activities 9

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

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

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

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

Overburden pre-mining 14 plan view – pre mining

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

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

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

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

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

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

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%