Bioleeching

Question 1

what is bioleaching

Answer 1

the utilisation of metal-oxidising and/or acid-generating microorganims to extract metals from ores

Question 2

why do we use bioleaching

Answer 2

low grade sulfide ores contain valuable metals but in low concentrations, its difficult and expensive to extract them via smelting so bioleaching it used to keep it cheap

Question 3

what metals does bioleaching target

Answer 3

Cu!!
(and Zn, Pb, As, Sb, Ni, Mo)

Question 4

Methods of bioleaching:

Answer 4

1. Dump bioleaching
2. Heap bioleaching

Question 5

what is dump bioleaching

Answer 5

acid added to piles of waste, indigenous bacteria proliferate, helps natural AMD along

Question 6

is dump bioleaching better or worse than heap bioleaching and why

Answer 6

worse because it is slow, ineffiecient and bacterial activity is not optimised

Question 7

what is heap bioleaching

Answer 7

finely crushed ores heaped to encourage aeration, solutions are re-cycled through the bioleaching process

Question 8

is heap bioleaching better or worse than dump bioleaching and why

Answer 8

better because it is more controlled than the dump method

Question 9

what is the process of heap bioleaching

Answer 9

1. spray heaps with sulfuric acid, bacteria, nutrients mixture
2. liquid treated in plant to precipitate and purify target metals
3. Fe2+ rich liquid then oxidised by microorganisms in ponds, then added to heaps

Question 10

variables that affect efficiency of bioleaching operations

Answer 10

1. Microbial action
2. temperature
3. pH
4. oxygen levels
5. nutrient availability
6. ore characteristics