Transcript Innovation Fund Project Commercial products from the Wild BARK

Ecological restoration of mining generated
wastelands using biochar technology: A potential
contribution to sustainable mining in Zambia
1Stephen
Syampungani, 2Olusegun Yerokun, 1Concilia Monde 1Wilson
Moono, Nancy Chileshe & Nalukui Matakala
1School
of Natural Resources, Copperbelt
University, Kitwe, Zambia
2Zambia
Open University, Lusaka
Degraded site
Preparation for
mining
Primary
forest/woodland
?
Stunted vegetation
Tailings
dam/Wasteland
Background
• Zambia has a mining history spanning over 90 years
 Largest copper deposits in
Africa_Zambia
 6% of known copper reserves
globally
 48% Zambia not geologically
surveyed
 Global consumption & demand for
most of the minerals_Projected
increase
Positive
 More employment/jobs???
 Massive infrastructure
 More money???
• Massive ecological foot print: Through generation of
wastelands:i) wasterocks, ii) overburden materials & iii)
tailings
Background: Some issues
• Mining generated wastelands:
– An environmental problem & wastage of land
– For example, Copperbelt alone
– 9,125 ha of wasteland
• contains 791 million tons of tailings
– and 20,146 ha
• Contain 1,899 million tons of overburden
materials
– Additional 388 & 279 ha
• contain 77 million tons & 40 millions of wasterock
and slag respectively
Background: Some issues
• Mining industry expanding in the recent past
– New deposits of copper and other minerals
such nickel, coal being discovered in many
parts of the country;
• Northwestern,
• Central &
• Southern Provinces
– More areas will be affected as need for more
dumping ground will increase_
• More mining generated wastelands
Background: some issues
• More and more generated wastelands remain unvegetated /poor /stunted vegetation for many years
Poor vegetation
Limited woody
plants
i) High toxicity arising from heavy metals
ii) Surface and ground water contamination
Background: Concepts
• Attempts to re-vegetate wastelands has
recorded more failures
• Recorded success:
– Species selection based on ability to grow
and adaptation
– Not ability to immobilize heavy metals
– No classification of species into classes
based on functional traits
• Excluders
• And accumulators
– Therefore, postponement of environmental
problem_approach
Approach in biochar technology application
Determination of
heavy metal
concentration
Cu, Co,Ba, Ni,
As,Zn, Pd, Cr, V,
Cd
& physical
properties
CU=
12,237.33±1746.87mg/kg
(Tailing samples )
7411.67±1317.53mg/kg
(Overburden samples)
Cd=0.60±0.23mg/kg and
0.25±0.13mg/kg on
tailings and overburden
material,
Pollution load factor=
8.97 and 5.84 on the tailings and overburden
material, respectively
Acidity (mean pH) =
6.0 and 4.7 for the tailings and overburden
material, respectively
Conclusion
•
•
•
•
The sites have high pollution load index
And are high contaminated
Very low porosity and no humus
The need for soil amendment
– biochar technology that enhance heavy metal
immobilization
•Reduced leaching on nitrogen
•Increased CEC in the soil
•Moderation of soil acidity
•Increased water holding capacity
•Increased number of soil beneficial biota
• Heavy metal immobilization & sequesteration
Biochar sources and soil amendments
• Biochar is partially corbonized organic waste:
– Wood chips
– Sawdust (100,000 m3
– Corncobs
– Chicken manure
– Various proportions of biochar and effect on soil are being
studied
BIOCHAR TECHNOLOGY AND SPECIES
CLASSIFICATION
BIOCHAR TECHNOLOGY
• Biochar technology to
be enhanced by
classification of
species:
– Accumulators/hyperaccu
mulators
– Excluders
CLASSIFICATION
Accumulators vs excluders
• Accumulars=
– absorbs metals
– and tend to accumulate heavy metals
– When dead heavy metals flows back into the ecosystem
• Excluders
– Exclude heavy metals from being absorbed
– Immobilize & sequester them
THANK YOU
Contact information:
[email protected];
[email protected]
+260979134305