Hydrometallurgy Acid Loops
There are many options on the approaches on how to achieve the recovery and refining of metals
from various streams of scrap materials ranging from mixed complex metals, micro electronics including
trace
and critical elements.
The Recovery 2.0
strategy
pursues a methodical "Concentration and Selective Extraction" approach.
One example of a systematic extractive metallurgy method to achieve the recovery and refining goals,
is a Hydrometallurgy
Acid
Loop.
(please note - this is just one scenario presented as an example.)
Following a Hydrometallurgy Acid Loop of sequential steps to identify and segregate highly mixed metals streams that
may vary widely in feedstock inputs must maintain a high degree of flexibility.
In this particular example we rely upon key a first stage of separation in a
Nitic Acid
loop,
the second stage utilizes a Hydrochloric Acid
(HCl)
Loop and a third stage in an
Aqua Regia
Loop.
Nitric Acid Loop
In the Nitric Acid Loop we take an incoming feedstock of separated metallic fraction from mixed
E-Scrap
and introduce it into the acid
leach tank
system.
The materials begin to group into three general classifications. A non-soluble solids fraction,
a fraction that directly precipices out of solution and a fraction of material that stay dissolved in solution.
Each of the three fraction streams are now ready for further concentration and selective extraction processing.
The non-soluble solids fraction may be routed into the second stage
HCl Loop
The other fractions may be sequentially separated by Oxidation/Reduction &
Displacement
processes according to the
Reactivity Series
sequentce.
Hydrometallurgy Acid Loops
Hydrochloric Acid (HCl)
e° = controled transfer of electron charge
| # | Sym | Element Name | Potential e° (V) | Melting Point | HCl |
| 4 | Be | Beryllium | + 2 e Be 1.97 | 1287 | BeCl2 |
| 13 | Al | Aluminium | + 3 e Al 1.68 | 660 | AlCl3 |
| 22 | Ti | Titanium | + 3 e Ti 1.37 | 1670 | TiCl3 |
| 15 | P | Phosphorous | e P 1.82 | 44 | non-soluble |
| 73 | Ta | Tantalum | +10 e Ta 0.75 | 2980 | non-soluble |
| 24 | Cr | Chromium | + 3 e Cr 0.74 | 1907 | CrCl3 |
| 31 | Ga | Gallium | + 3 e Ga 0.55 | 30 | GaCl3 |
| 41 | Nb | Niobium | +3 e Nb 1.099 | 2477 | non-soluble |
| 44 | Ru | Ruthenium | + 3 e Ru +0.60 | 2333 | non-soluble |
| 45 | Rh | Rhodium | + 3 e Rh +0.76 | 1963 | non-soluble |
| 76 | Os | Osmium | 91.4 | 3000 | non-soluble |
| 46 | Pd | Palladium | + 2 e Pd +0.92 | 1555 | PdCl4 |
| 77 | Ir | Iridium | + 3 e Ir +1.0 | 2446 | non-soluble |
| 78 | Pt | Platinum | + 2 e Pt +1.18 | 1768 | non-soluble |
| 79 | Au | Gold | + 3 e Au +1.50 | 1064 | non-soluble |
| 74 | W | Tungsten | +4 e W 0.12 | 3400 | non-soluble |
Hydrochloric Acid (HCl) Loop
The non-soluble solids fraction remaining after the
Nitric Acid
loop may be rinsed and leached in the
HCl
loop.
Those materials that are successfully dissolved in the HCl loop may proceed to be concentrated and selectively extracted
into the individual refined metals.
Those remaining materials in the non-soluble fraction may proceed to the
Aqua Regia
loop.
Aqua Regia
( HNO + 3HCl )
e° = controled transfer of electron charge
| # | Sym | Element Name | Potential e° (V) | Melting Point | Aqua Regia |
| 73 | Ta | Tantalum | +10 e Ta 0.75 | 2980 | non-soluble |
| 44 | Ru | Ruthenium | + 3 e Ru +0.60 | 2333 | non-soluble |
| 45 | Rh | Rhodium | + 3 e Rh +0.76 | 1963 | non-soluble |
| 76 | Os | Osmium | 91.4 | 3000 | non-soluble |
| 77 | Ir | Iridium | + 3 e Ir +1.0 | 2446 | non-soluble |
| 78 | Pt | Platinum | + 2 e Pt +1.18 | 1768 | H2PtCl4 |
| 79 | Au | Gold | + 3 e Au +1.50 | 1064 | 2HAuCl4 |
| 74 | W | Tungsten | +4 e W 0.12 | 3400 | non-soluble |
Aqua Regia Loop
The Aqua Regia Loop is targeted at those materials that did not dissolve in the first stage
Nitric Acid
and also did not dissolve in the
HCl
second stage loop.
This third stage loop is tasked for the disposition of the few remaining items left over from the first two stages of processing.
This group of materials tends to be a small
select group
of elements that may require specialized treatment.
In most cases this additional or customized treatment may need to be justified.
A further
Sulfuric Acid Loop
may be employed for the advanced treatment, potential selective segragation and refining of
Niobium, Tantalum and Tungsten.
As an alternative, The non-soluble solid fraction remaining after the Aqua Regia acid treatment may be further segragated by a
Density Separation stage.
Density Separation
for Aqua Regia Loop Rejects
| # | Sym | Element Name | Density - grams/cm³ |
| 41 | Nb | Niobium | 8.57 |
| 45 | Rh | Rhodium | 12.41 |
| 44 | Ru | Ruthenium | 12.42 |
| 73 | Ta | Tantalum | 16.65 |
| 74 | W | Tungsten | 19.3 |
| 77 | Ir | Iridium | 22.56 |
Sulfuric Acid Loop
After the sequential treatment of a nitic acid loop, a Hydrochloric Acid (HCl) loop and an
Aqua Regia loop the remaining non-soluble solid fraction may be treated by a
further Sulfuric Acid Loop to achieve selective segragation
Niobium, Tantalum and Tungsten.
Sulfuric Acid Loop
e° = controled transfer of electron charge
| # | Sym | Element Name | Potential e° (V) | Melting Point | Sulfric Acid |
| 73 | Ta | Tantalum | +10 e Ta 0.75 | 2980 | Ta(SO4)2 |
| 41 | Nb | Niobium | +3 e Nb 1.099 | 2477 | Nb2(SO4)5 |
| 44 | Ru | Ruthenium | + 3 e Ru +0.60 | 2333 | non-soluble |
| 45 | Rh | Rhodium | + 3 e Rh +0.76 | 1963 | Rh2(SO4)3 |
| 77 | Ir | Iridium | + 3 e Ir +1.0 | 2446 | non-soluble |
| 74 | W | Tungsten | +4 e W 0.12 | 3400 | non-soluble |
