Alumina Recovery
The recovery of Alumina or Aluminum Oxide typically refers to
Al2O3
but may contain other oxide matrix materials.
Alumina is a common constituent in pigments,
refractory
materials and may be a replacement or a substitute for raw
Bauxite
Aluminum Oxides
may be reclaimed as a by-product of metal processing, smelting, refining and
recovery
operations.
The conversion of Aluminum Oxide into Aluminum metal traditionally has involved the generation of CO2.
One method of carbon free aluminum oxide reduction may be by using a
REDOX Displacement
reaction.
Aluminum Salt Cake Recovery
Aluminum Oxide recovery from dross recovery salt cake byproducts,
a process to dissolve the aluminum salt cake residue into a
Brine Solution.
Brine Solutions shall consist of liquid solutions containing sodium chloride.
Separation or filtration of the non-soluble sediment which contains
Aluminum Oxides
and the residual brine is sent for
De-Salination
to purify the water.
A byproduct of the aluminum recovery process from dross is
Aluminum Salt Cakes.
Aluminum Salt Cakes shall consist of sodium chloride blocks, chunks or bricks from aluminum dross recovery operations
and may contain various quantities of Aluminum or Aluminum Oxides
Aluminium vs. Aluminum
Is it Aluminium or Aluminum ?
UK & Euro pronounce & spell Aluminium vs. North American which refers to Aluminum.
It's the same stuff
Aluminum Silicates Recycling
There are a broad number of mineral sources that generate Aluminum Silicate byproducts and materials,
and these materials vary widely in the matrix make-up that characterize these
Aluminum Silicate Residues.
Aluminum silicate (aluminium silicate or aluminosilicate) are the names commonly applied to a group of chemical compounds
which consist mainly of aluminium oxide
(Al2O3)
and silicon dioxide
(SiO2)
Recovered
Zeolites
(a subset group of Aluminum silicate based minerals) may be beneficial in the efforts to
De-Carbonize the energy infrastructure.
Generated from sources such as :
Residual Aluminosilicate Materials
Red Mud
Red Mud is produced as a byproduct of the Bayer process in the conversion of bauxite into alumina in the preparation
of the raw materials in the Aluminum Metal Refining process.
It is estimated that between 1 to 1.5 tonnes of
Red Mud
is generated for each Metric Tonne of alumina produced,
and 2 ton of alumina is required to produce one tonne of Aluminum Metal.
It is also estimated that over 3 billion tons of Red Mud worldwide has been accumulated and is stored in what is referred to as
bauxite residue tailings monofills and slurry ponds.
Aluminum production accounts for the approximate current generation rate of an additional 150 million tons of Red Mud each year.
On average between 4-5 tonnes of bauxite is required to be produced into 2 tonnes of alumina
which yields 1 tonne of metallic aluminium output,
so this process generates between 2-3 tonnes of Red Mud for each tonne of Aluminum Metal.
Typical Red Mud Composition
| Symbol | Item Name | Range % |
| Fe2O3 | Iron Oxide | 5-60% |
| Al2O3 | Aluminium Oxide | 5-30% |
| TiO2 | Titanium Dioxide | 0-15% |
| CaO | Calcium Oxide | 2-14% |
| SiO2 | Silicon Dioxide | 3-50% |
| Na2O | Sodium Oxide | 1-10% |
|
Trace Elements |
Mixed Heavy Metals | 0.5-13.0% |
Red Mud Contents
A general average chemical analysis of Red Mud may contain silica, aluminum, iron, calcium, titanium, as well
as an array of minor constituents such as
REEs
Na, K, Cr, V, Ni, Ba, Cu, Mn, Pb, Zn etc.
The chemical composition between different Red Muds worldwide vary widely.
A complex matrix of materials such as this may be selectively extracted through a process such as the
Recovery 2.0 -
oxide reduction
system in order to valorize the resources contained in these residual byproducts.
Fly Ash
Fly Ash may be viewed as a type of
Aluminum Silicate
Residue.
There are a variety of types of ash including coal ash and
Incinerator Ash.
Incinerator ashes are typically designated into Incinerator Bottom Ash (IBA) and
flue gas stack Fly Ash.
These Ashes may be further classified into Class F Fly Ash and Class C Fly Ash.
Class C fly ash generally contains more than 20% lime (CaO) and Class F fly ash
contains a lower lime (CaO) content.
Fly Ash may be used as a
Circular Aggregate
in the production of
geopolymer concrete.
The chemical composition of
fly ash
depends upon the type of combustion fuel used and the methods used in the combustion process.
Chemical Composition of Fly Ash
| Symbol | Item Name | Range % |
| SiO2 | Silicon Dioxide | 55-65 % |
| Al2O3 | Aluminium Oxide | 25-35 % |
| Fe2O3 | Iron & Iron Oxides | 1.5-4.0 % |
| MnO2 | Manganese DiOxide | 0.0-0.20 % |
| CaO | Calcium Oxide | 1.5-10 % |
| MgO | Magnesium Oxide | 0.5-2.50 % |
| K2O | Potassium Oxide | 0.0-1.0 % |
| TiO2 | Titanium Dioxide | 0.5-2.0 % |
| Na2O | Sodium Oxide | 0.1-1.0 % |
|
Trace Elements |
Mixed Heavy Metals | 0.1-8.5% |
| LOI | Loss on Ignition | 0.1-15.0 % |
Increased levels in carbon content can make the fly ash unsuitable for the use in the production of geopolymer concrete. The ASTM C618 specification limits loss-on-ignition (LOI) to 6% to be an acceptable as a geopolymer material.
Furnace Slags
It is not uncommon for a melting furnace to utilize limestone as a part of the melting/reducing process.
The molten limestone acts as a carrier for the accumulation of any impurities collected from within the process
and is expelled as a molten slag.
The main components of blast
furnace slag
are CaO (30-50%), SiO2 (28-38%), Al2O3 (8-24%), MnO, and MgO (1-18%).
These slags are typically grouped into a classification included as
Aluminum Silicates
Residues.
One common reuse of slag materials is as a blend that is integrated into Recycled
Aggregates
in the form of materials such as Ground Granulated Blast Furnace Slag (GGBS).
Typical Furnace Slag Composition
| Symbol | Item Name | Range % |
| CaO | Calcium Oxide | 30-50% |
| SiO2 | Silicon Dioxide | 28-38% |
| Al2O3 | Aluminium Oxide | 8-24% |
| MgO | Magnesium Oxide | 1-18% |
| MnO | Manganese Oxide | ~ ~ |
| Fe2O3 | Iron & Iron Oxides | ~ ~ |
|
Trace Elements |
Mixed Heavy Metals | 0.3-9.0% |
