Description:Field of the Invention
The present invention relates to processes for recovering aluminium and
value-added products from aluminium dross waste, and more particularly to a
zero-waste process for separating metallic aluminium and producing composite
materials from aluminium dross residue using nanotechnology and inductive
heating.
Background of the Invention
Every primary aluminium producer, remelter, or recycler faces the reality
that dross forms when molten aluminium comes into contact with air during any
process. Aluminium dross is formed whenever aluminium or aluminium alloy is
melted and held in the liquid state, during alloying and refining treatment
processes and casting under oxidizing atmosphere. Aluminium dross is also
formed in larger quantities during the remelting of process scrap and the
recycling of post-consumer aluminium products. 'Dross' refers to the mass of
solid impurities, including aluminium oxide and recoverable aluminium metal,
floating on the surface of the molten metal in a furnace. Freshly removed dross
is hot, but most processing methods are applied to cooled dross, which is often
transported long distances for processing. The dross is subsequently removed
periodically through skimming or similar operations. Upon removal, the dross
typically exists as a pasty or granular material, at or above the furnace
2
temperature, and contains a significant quantity of free aluminium metal,
aluminium oxide, and other non-metallic compounds.
Aluminium dross is a byproduct generated during the production and
recycling of aluminium. It typically consists of a mixture of aluminium metal,
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aluminium oxides, and other compounds. The management and disposal of
aluminium dross presents environmental and economic challenges for the
aluminium industry.
Aluminium drosses are categorized based on the concentration of
NaCl/KCl salt contained therein. In primary aluminium production processes,
the use of salt is either minimal or absent, resulting in dross commonly referred
to as "white dross." In contrast, in secondary refining and aluminium dross
processing, the use of NaCl/KCl salt is more prevalent. The incorporation of salt
enhances the interfacial tension between the dross and aluminium, thereby
facilitating the coalescence of metallic aluminium and improving its separation
from the oxide. Furthermore, salt serves to protect the liquid aluminium from
atmospheric exposure, thereby reducing the propensity for further oxidation.
The dross produced in such processes, which contain elevated levels of salt, is
designated as "black dross."
During aluminium production and recycling processes, a layer of dross
forms on the surface of molten aluminium. This dross contains valuable
3
aluminium metal along with oxides and impurities. The amount of dross
generated can range from 2-10% of the total aluminium processed, depending
on the specific production methods used.
For reasons of cost efficiency, it is desirable to recover as much of the
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free metal carried from the furnace in the dross as possible in a usable form.
However, the separation of the metal proves challenging, as it is dispersed
throughout the dross in the form of fine particles or globules, intimately mixed
with and surrounded by the non-metallic components of the dross. Additionally,
the free metal within the porous structure of the dross is highly susceptible to
oxidation, particularly at elevated temperatures. Specifically, the dross at
furnace temperature frequently tends to ignite and burn, resulting in a rapid
reduction of the recoverable free metal content.
Aluminium Dross, a by-product of aluminium production, is a worldwide
problem. Approximately 5 million tons of aluminium dross and salt cake
materials are landfilled annually in the world. Majority of dross is disposed of
in landfill sites, which is likely to result in leaching of toxic metal ions into
ground water causing serious pollution problems. There are two forms of dross – white dross and black dross. White dross is formed during the primary Al
refining process, while black dross is formed during the secondary refining
process, which uses relatively substantial amounts of chloride salt fluxes.
4
Subsequently, the dross is processed in rotary kilns to recover the Al, and the
resultant salt cake is sent to landfills. Although salt cakes are sealed to prevent
leaching, the potential for leaks exists and in fact does occur which harms the
environment. There is much merit if the dross that is formed could be “recycled”
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as an engineering product for specific applications.
Traditionally, aluminium dross has been treated as a waste product and
disposed of in landfills. However, this practice is problematic from both
environmental and economic perspectives. Landfilling of aluminium dross can
lead to leaching of potentially harmful substances into soil and groundwater.
Additionally, the aluminium metal content of dross represents a loss of valuable
raw material when it is discarded.
Landfilling of aluminium dross obtained from primary/secondary
aluminium industries leads to severe environmental pollution. The amount of
toxic leachable salts is quite high in saline slags and salt cakes, which makes
these wastes potential water pollutants. The environmental impacts of
aluminium dross are detrimental. When dross comes in contact with water,
hazardous gases are released including ammonia, which pollutes the atmosphere
Due to the water contamination around the landfilling sites, flora and fauna get
disturbed, further upsetting the ecological balance. Landfilling of aluminium
waste products can be done only when the leaching of waste is avoided by
5
sealing the waste products properly. Therefore, proper measures are necessary
while disposing of aluminium waste materials.
Interestingly the main constituents of dross are Al and Al2O3, yet
ironically, and MgO and MgAl2O4 as well, since there is much effort today to
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produce Al-based composites containing a second phase constituent (such as
Al2O3). Typically, the chemical composition of aluminium dross contains
aluminium (5-30%), aluminium oxide (30-50%), silica (3-7%), Magnesium (3
5%), zinc (3-15%), copper (5-10%), chlorine (0-2%), fluorine (1-15%). The
currently available technologies for aluminium dross recovery have several
disadvantages, including a low recovery rate, severe environmental pollution,
high labor intensity, negative health impacts, and high energy consumption.
Although the known methods have their own advantages, however there is no
commercially available technology for recovery of 100% of aluminium dross to
useful products.
In recent years, there has been increasing interest in developing methods
to recover aluminium and other useful materials from dross. Some approaches
involve mechanical separation techniques to extract metallic aluminium. Other
processes use chemical treatments to convert aluminium compounds in dross
into value-added products. However, many existing dross processing methods
still generate secondary waste streams that require disposal.
6
The aluminium industry continues to seek improved technologies for
managing dross in ways that maximize material recovery and minimize
environmental impacts. Developing economically viable processes to extract
multiple useful products from dross, while generating minimal waste, remains
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an active area of research and development.
Effective utilization of aluminium dross has the potential to improve the
sustainability and efficiency of aluminium production. Recovering aluminium
metal from dross can offset the need for primary aluminium production, which
is an energy-intensive process. Additionally, converting dross components into
saleable products creates new value streams for aluminium producers.
To address the above limitations, there is a need for technologies that can
process dross in a "zero waste" manner is particularly desirable from both
environmental and economic standpoints. Hence it can be concluded that zero
waste process is an environmentally friendly, and economic benefit, which is the
need of the hour.
Objects of the invention
The objective of the present invention is to provide a facile and robust
process for extraction of aluminium values from the Aluminium dross residue.
The aluminium dross was subjected to inductive heating using aluminium
nanoparticles to obtain the metallic aluminium.
7
Another object of the present invention is to provide an efficient process
for the producing of value-added products from the residual powder.
Summary of the Invention
This summary is provided to introduce a selection of concepts in a
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simplified form that are further described below in the detailed description.
This summary is not intended to identify key features or essential features of
the claimed subject matter, nor is it intended to be used as an aid in
determining the scope of the claimed subject matter.
According to an aspect of the present invention, a process for the recovery
of aluminium values from aluminium dross residue is provided. The process
comprises utilizing aluminium nanoparticles and inductive heating followed by
separation of metallic material from the residual powder.
According to another aspect of the present invention, a process for the
utilization of aluminium dross is provided. The process comprises separating
metallic lumps from residual powder and subjecting the metallic lumps to
inductive heating using aluminium nanoparticles. The residual powder is used
for various applications.
According to other aspects of the present invention, the process may
include one or more of the following features. The mixture of aluminium dross
with aluminium nanoparticles may be subjected to heating. The heating devices
8
may include muffle furnaces and inductive furnaces. The temperature of heating
may be from 400-1000°C. The heating time may vary from 30-300 minutes.
After treatment with inductive heating using the aluminium nanoparticles, it may
result in the formation of metallic material which is separated.
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The process may include conversion of residual powder to various
composite materials. The composite material obtained after the treatment may
be utilized for various applications such as water treatment, fluoride removal,
arsenic removal, and pharma effluent water treatment.
The residual dross powder may be washed with water to remove the
soluble salts at room temperature to 100°C. The water may be filtered and
purified by water treatment using known methods and utilized for washing
purposes.
The washed residual dross may be further dried and utilized by making
composite materials which may be used for the removal of fluoride and arsenic
from water. The arsenic in water may be reduced from 500-1000 ppb to 50-100
ppb in the process and fluoride may be reduced from 5 ppm to 0.2 ppm.
The COD (10-15K ppm) in the wastewater may be reduced to 5-6K ppm
when treated with dross powder. The wastewater may include pharma effluent
water, textile effluent, coke oven effluent, and coffee effluent.
9
The foregoing general description of the illustrative embodiments and the
following detailed description thereof are merely exemplary aspects of the
teachings of this invention and are not restrictive.
Brief Description of the Figures
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Non-limiting and non-exhaustive examples are described with reference
to the following figures.
Fig. 1 shows an innovative process flow chart for recovering aluminium
and value-added products.
Fig. 2 shows schematic representation of innovation process for
recovering aluminium and value-added products.
Fig. 3 shows a system for recovering aluminium and value-added
products.
Detailed Description of the Invention
The following description sets forth exemplary aspects of the present
invention. It should be recognized, however, that such a description is not
intended as a limitation on the scope of the present invention. Rather, the
description also encompasses combinations and modifications to those
exemplary aspects described herein.
The present invention relates to processes and systems for recovering
aluminium and producing value-added products from aluminium dross waste. In
10
an example, the processes and systems described herein may provide a zero
waste approach to handling aluminium dross, which may be a byproduct of
aluminium production.
In one embodiment of the invention, Fig. 1 shows that the innovative
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process flow chart for recovering aluminium and value-added products from
aluminium dross may involve multiple interconnected steps that work together
to create a zero-waste system. This integrated approach may allow for efficient
resource recovery while minimizing environmental impact.
In this embodiment, the process may begin with the separation of 220 kg
of metallic lumps from 450 kg of residual powder in the aluminium dross. This
separation step may be crucial for directing different components of the dross to
appropriate processing pathways.
The metallic lumps separated from the dross may then undergo treatment
with aluminium nanoparticles. This treatment step may enhance the subsequent
recovery of 8.6 Kg of metallic aluminium by potentially improving the
efficiency of the heating process.
An embodiment of the invention is that the aluminium nanoparticle size
may vary from 100nm-1000nm, preferably 100-300 nm. The addition of
aluminium nanoparticles during the melting process to achieve 95-99% purity
and 70-90% efficiency of metallic aluminium recovery.
11
Following treatment, the metallic lumps may be subjected to inductive
heating. The mixture was heated to 700-1200°C using an inductive furnace or
muffle furnace. The preferable temperature is 900-1100°C. This heating process
may facilitate the recovery of metallic aluminium, which may be collected for
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reuse or further processing.
Meanwhile, 230 Kg of residual powder separated in the initial step may
be directed to a conversion process. This conversion may involve washing the
powder with water to remove soluble salts, followed by mixing with metallic
materials and heating to create composite materials. The combination of multi
stage dross treatment, use of nanoparticles, sequential heating process, and
conversion of waste into value-added products to improve aluminium recovery
and zero waste.
In one embodiment of the invention, the aluminium dross is treated with
water to remove the soluble salts. The slurry is dried at 90-100°C for 18-24 h.
The water content showed pH 8.0-9.0, total dissolved salts (1200-1800), and
Fluoride (25-30 ppm).
In another embodiment, the residual powder was mixed with metallic
materials such as aluminium, copper, copper oxide, copper-nickel alloy, copper
zinc alloy, iron, iron oxide, zinc, zinc oxide, chitosan, alginate, red mud, and
heating in an induction or muffle furnace. Induction furnaces are not only used
12
as a source of heating but also to induce an alternating frequency magnetic field,
which is suitable for the selective heating of metals used.
The metallic portion of the dross was subjected to inductive heating with
the voltage 300V-450V and frequency 400-1500 Hz, but the ideal is used around
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nearly 900-1000 Hz. Preferred is the use of crucibles selected from iron, stainless
steel, graphite, quartz and ceramic for induction heating.
In another embodiment of the invention, crucibles such as graphite,
ceramic, stainless steel, quartz and iron are suitable, which are heated by 380V,
900-1200 Hz industrial electricity, whereas the heating power is controlled by
setting of the desired temperature.
The composite materials produced from the residual powder may find
applications in water treatment, potentially addressing environmental challenges
associated with wastewater contamination. This utilization of what might
otherwise be considered waste may contribute to the zero-waste nature of the
process.
The present invention relates to processes and system for recovering
aluminium and producing value-added products from aluminium dross waste. In
an example, the processes and system described herein may provide a zero-waste
approach to handling aluminium dross, which may be a byproduct of aluminium
production.
13
The processes may involve separating metallic components from residual
powder in the aluminium dross. In an example, the metallic components may be
treated and processed to recover metallic aluminium. The residual powder,
which may otherwise be considered waste, may be converted into various useful
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products.
In this embodiment, the residual powder may be used to create composite
materials for water treatment applications. These composite materials may be
effective in removing contaminants from wastewater, potentially providing
environmental benefits.
Additionally, the residual powder may be utilized to create slag materials
for the steel industry. This application may further contribute to the zero-waste
nature of the process by finding a productive use for what would typically be
considered a waste product.
The processes and systems described herein may offer potential benefits
in terms of resource recovery, waste reduction, and environmental protection.
By recovering aluminium and creating value-added products from aluminium
dross, these approaches may help to address challenges associated with
aluminium dross disposal while potentially providing economic and
environmental advantages.
14
Fig. 2 shows an embodiment of the invention is the process of recovering
aluminium and value-added products from aluminium dross may begin with the
separation of 220kg metallic lumps from 450kg residual powder. This separation
step may be crucial for efficient processing and recovery of materials from the
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aluminium dross.
In an example, the aluminium dross may be subjected to a preprocessing
step before separation. This preprocessing may involve crushing or grinding the
dross to reduce particle size and improve the efficiency of subsequent separation
techniques. The crushing or grinding may be performed using various types of
equipment such as jaw crushers, ball mills, or hammer mills, depending on the
characteristics of the dross and the desired particle size distribution.
After preprocessing, various separation techniques may be employed to
separate the metallic lumps from the residual powder. One common method may
involve sieving or screening the crushed dross through a series of sieves with
different mesh sizes. This technique may allow for the separation of particles
based on size, with larger metallic lumps being retained on coarser sieves while
finer residual powder passes through to finer sieves.
In an example, magnetic separation may be used to separate
ferromagnetic materials from non-magnetic components in the dross. This
15
technique may be particularly effective if the dross contains iron or steel
contaminants that need to be removed before further processing.
Another separation method that may be employed is air classification. In
this technique, the crushed dross may be fed into a vertical air stream. The lighter
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residual powder particles may be carried upward by the air current and collected
separately, while the heavier metallic lumps fall and are collected at the bottom
of the classifier.
Density-based separation techniques, such as sink-float separation, may
also be used in some cases. This method may involve immersing the dross in a
liquid medium with a specific gravity between that of the metallic aluminium
and the oxide residues. The metallic lumps, being denser, may sink to the
bottom, while the lighter residual powder floats and can be skimmed off the
surface.
The effectiveness of these separation techniques may vary depending on
the composition and characteristics of the aluminium dross being processed. In
one embodiment of the invention, a combination of multiple separation methods
may be used to achieve optimal separation of metallic lumps from residual
powder.
After separation, the metallic lumps may be collected for further
processing to recover metallic aluminium, while the residual powder may be
16
directed to other processing steps for conversion into value-added products. This
separation step may help ensure that each component of the aluminium dross is
processed in the most appropriate manner, potentially maximizing resource
recovery and minimizing waste.
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The treatment of metallic lumps with aluminium nanoparticles may be a
key step in the process of recovering aluminium from aluminium dross. In an
embodiment of the invention, the metallic lumps separated from the aluminium
dross may be mixed with aluminium nanoparticles to enhance the recovery
process.
The aluminium nanoparticles used in this treatment process may have a
size ranging from 100 to 1000 nanometers (nm). In another embodiment of the
invention, smaller nanoparticles within this range, such as those between 100
and 300 nm, may be utilized. The size of the nanoparticles may affect the
efficiency of the treatment process and the quality of the recovered aluminium.
Various methods may be employed to mix the metallic lumps with the
aluminium nanoparticles. In an example embodiment of the invention,
mechanical mixing techniques may be used, such as ball milling or high-shear
mixing. These methods may help to ensure uniform distribution of the
nanoparticles throughout the metallic lump material.
17
The rationale behind using aluminium nanoparticles in this treatment
process may be multifaceted. Nanoparticles may have a high surface area to
volume ratio, which may increase their reactivity and interaction with the
metallic lumps. This enhanced interaction may facilitate the separation of
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aluminium from other components in the dross during subsequent processing
steps.
In one embodiment of the invention, the use of nanoparticles may also
help to lower the processing temperature required in later stages, potentially
reducing energy consumption and improving the overall efficiency of the
recovery process.
The effects of different nanoparticle sizes on the treatment process may
vary. For example, nanoparticles in the range of 100-300 nm may provide a
balance between reactivity and ease of handling. Larger nanoparticles, such as
those in the 500-1000 nm range, may offer different benefits, such as potentially
easier recovery after the treatment process.
In some implementations, a treatment unit may be used for mixing the
metallic lumps with aluminium nanoparticles. This unit may be designed to
ensure thorough and uniform mixing of the components. The treatment unit may
incorporate features such as temperature control or inert gas purging to prevent
oxidation during the mixing process.
18
The duration of the treatment process may vary depending on factors such
as the size and composition of the metallic lumps, the size of the nanoparticles
used, and the desired outcome of the treatment. The addition of aluminium
nanoparticles during the melting process to improve the purity or efficiency of
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metallic aluminium recovery.
In another embodiment of the invention, the treatment may be carried out
for a period ranging from several minutes to several hours.
After the treatment process, the mixture of metallic lumps and aluminium
nanoparticles may be ready for subsequent processing steps, such as inductive
heating, to further recover the aluminium content.
The inductive heating process may be a key step in recovering metallic
aluminium from the treated metallic lumps. In an embodiment of the invention,
an inductive heating unit may be used to heat the treated metallic lumps to
temperatures sufficient for aluminium recovery.
The inductive heating unit may operate within specific voltage and
frequency ranges. In some implementations, the voltage may range from 300V
to 450V, while the frequency may range from 400 Hz to 1500 Hz. These
parameters may be adjusted based on the specific characteristics of the treated
metallic lumps and the desired recovery efficiency.
19
The temperature range for the inductive heating process may vary. In
another embodiment of the invention, the inductive heating may be performed
at temperatures between 700°C and 1200°C. More specifically, the temperature
range may be narrowed to between 900°C and 1100°C in certain
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implementations. The selection of the appropriate temperature range may
depend on factors such as the composition of the treated metallic lumps and the
desired purity of the recovered aluminium.
The duration of the inductive heating process may also vary. In an
example, the heating duration may range from 15 minutes to 60 minutes. The
optimal heating time may depend on factors such as the mass of the treated
metallic lumps, the temperature used, and the desired recovery efficiency.
In some implementations, different types of crucibles may be used in the
inductive heating unit. These may include crucibles made from materials such
as graphite, ceramic, quartz, stainless steel, or iron. The choice of crucible
material may affect the heating efficiency and the purity of the recovered
aluminium.
While an inductive heating unit may be commonly used, in some cases,
a muffle furnace may be employed instead. The muffle furnace may offer
different heating characteristics and may be suitable for certain types of treated
metallic lumps or specific recovery requirements.
20
The efficiency of aluminium recovery may be influenced by various
parameters of the inductive heating process. For example, higher temperatures
within the specified range may lead to faster recovery but may also increase
energy consumption. Lower frequencies may result in deeper heating of the
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treated metallic lumps, potentially improving recovery from larger pieces.
In some implementations, the inductive heating process may be
performed in stages. For instance, an initial heating stage at a lower temperature
may be followed by a higher temperature stage to optimize recovery efficiency
while minimizing energy consumption.
The recovered metallic aluminium may be collected in various forms
depending on the specific parameters of the inductive heating process. In an
example, the aluminium may be collected as a molten pool at the bottom of the
crucible, while in other cases, it may form solid ingots or granules.
After the inductive heating process, the recovered aluminium may
undergo further refining steps to achieve the desired purity level. These
additional steps may include techniques such as flux treatment or gas purging to
remove residual impurities.
The processing of residual powder from aluminium dross may involve
several steps to convert it into value-added products. In this invention, the
residual powder may be washed with water to remove soluble salts prior to
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further processing. This washing step may help to purify the residual powder
and prepare it for conversion into composite materials.
The washing process may involve mixing the residual powder with water
in a washing unit. The ratio of water to residual powder may vary depending on
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the specific characteristics of the powder and the desired level of salt removal.
In some implementations, multiple washing cycles may be employed to achieve
a higher degree of salt removal.
After washing, the residual powder may be dried to remove excess
moisture. Various drying methods may be used, such as air drying, oven drying,
or spray drying. The choice of drying method may depend on factors such as the
volume of material being processed and the desired characteristics of the dried
powder.
Once dried, the residual powder may be converted into various composite
materials. In an embodiment of the invention, the dried residual powder may be
mixed with one or more metallic materials to create these composites. The
metallic materials may include, but are not limited to, copper, copper oxide, iron,
iron oxide, zinc, zinc oxide, chitosan, and alginate.
The mixing process may be carried out using various techniques, such as
mechanical mixing, ball milling, or high-shear mixing. The choice of mixing
22
technique may depend on the specific materials being combined and the desired
properties of the final composite.
In some implementations, the mixture of dried residual powder and
metallic materials may be subjected to heating to form the final composite
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material. The heating process may be carried out at temperatures ranging from
400°C to 1000°C. The specific temperature used may depend on factors such as
the composition of the mixture and the desired properties of the final composite.
The heating process may be carried out in various types of furnaces or
heating units. In another embodiment of the invention, crucibles made from
materials such as graphite, iron, aluminium, or silica may be used to contain the
mixture during heating. The choice of crucible material may depend on factors
such as the heating temperature and the chemical compatibility with the mixture
being heated.
The duration of the heating process may vary, with some
implementations using heating times ranging from 15 to 60 minutes. The
specific heating time may be adjusted based on factors such as the composition
of the mixture, the heating temperature, and the desired properties of the final
composite.
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The combination of multi-stage dross treatment, use of nanoparticles,
sequential heating process, and conversion of waste into value-added products
to improve the aluminium recovery and zero waste.
In an embodiment of the invention, the process of creating composite
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materials may involve the use of specific chemicals. For example, when creating
composites with chitosan or alginate, sodium hydroxide may be used in the
process. The use of sodium hydroxide may help to dissolve these materials and
facilitate their incorporation into the composite.
The composite materials produced from the residual powder may have
various applications, particularly in water treatment. These materials may be
effective in removing contaminants from wastewater, potentially providing
environmental benefits.
The specific properties and applications of the composite materials may
vary depending on the composition and processing conditions. For example,
composites containing copper or copper oxide may have different properties and
applications compared to those containing iron or iron oxide.
In some implementations, a conversion unit may be used to process the
residual powder into composite materials. This unit may be designed to carry
out the various steps involved in the conversion process, including mixing,
heating, and potentially cooling or post-processing steps.
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The conversion unit may be integrated with other components of the
processing system, such as the washing unit. This integration may allow for
efficient processing of the residual powder from its initial state through to the
final composite material.
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By processing the residual powder into value-added products, this
approach may help to maximize resource recovery from aluminium dross while
potentially providing materials with useful applications in areas such as water
treatment.
The composite materials produced from aluminium dross residual
powder may have various applications in water treatment. In some cases, these
materials may be effective in removing contaminants from wastewater,
potentially providing environmental benefits.
In some implementations, the composite materials may be used to treat
wastewater containing contaminants such as arsenic, fluoride, and chemical
oxygen demand (COD). The treatment process may involve contacting the
composite material with the contaminated wastewater, allowing for the removal
or reduction of these contaminants.
Table 1: Water treatment using EMRION technology (patent reference)
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S.
No
Parameter
Initial Conc. (ppm) Final Conc. (ppm)
1
pH
8
6.5
2
Total dissolved salts
1550
850
3
Chlorides
40
5.0
4
Fluoride
31
1.5
5
Ammonia
49
<1
6
Hardness
85
25
Table 2: Fluoride removal using new composite material prepared as per
claims
Fluoride removal may also be achieved using these composite materials. In some
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implementations, the materials may be able to reduce fluoride concentrations
from initial levels of 5 parts per million (ppm) to final levels of 0.2 ppm. This
reduction may be particularly beneficial in areas where high fluoride levels in
water pose health risks.
Fluoride (ppm)
# Sample name
1 ALD 1
Time
Before After
3.0
3.0
1 h
26
2 ALD 2
3.0
3.0
3 ALD 3
2.0
1 h
0.5
4 ALD 9
2.0
1 h
0.0
5
3.0
1 h
0.2
6 ALD 10
3.0
1 h
0.5
7
1.0
1 h
0.0
8
0.5
1 h
0.0
9 ALD 11
3.0
30
1.5
1 h
For arsenic removal, the composite materials may demonstrate
significant efficacy. In an embodiment of the invention, the materials may be
capable of reducing arsenic concentrations from initial levels of 500-1000 parts
per billion (ppb) to final levels of 50-100 ppb. This reduction may represent a
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substantial improvement in water quality, potentially bringing arsenic levels
closer to or within acceptable limits for various uses.
Table 3: Arsenic removal using composite materials prepared as per
claims
Arsenic (ppm)
# Sample name
1 ALD 1
Time
Before After
2.0
0.5
1 h
27
2
1.0
0.1
3
0.5
1 h
0.0
4 ALD 2
2.0
30
0.5
5
1.0
1 h
0.2
6
0.5
1 h
0.0
78 ALD 3
2.0
30
0.5
8
1.0
1 h
0.0
9
0.5
1 h
0.0
10 ALD 4
2.0
30
0.5
11
1.0
1 h
0.2
12
0.5
1 h
0.0
13 ALD 5
2.0
30
1.0
14
1.0
1 h
0.6
15
0.5
1 h
0.0
16 ALD 6
2.0
30
1.0
17
1.0
1 h
0.5
18
0.5
1 h
0.0
19 ALD 7
2.0
30
1.0
20
1.0
1 h
0.5
1 h
28
21
0.5
0.0
22 ALD 8
2.0
30
2.0
23 ALD 11
2.0
1 h
0.0
24
1.0
1 h
0.0
25
0.5
1 h
0.0
30
The composite materials may also be effective in reducing chemical
oxygen demand (COD) in wastewater. COD may be an important indicator of
organic pollutants in water, and its reduction may be crucial for improving
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overall water quality. While specific reduction levels may vary depending on the
initial COD concentration and the particular composite material used, significant
reductions may be achievable in many cases.
The composite materials may be applied to treat various types of
industrial wastewater. For example, they may be used in treating pharmaceutical
effluent, which may contain a complex mixture of organic compounds and other
contaminants. In an example, materials may be effective in reducing COD levels
in pharmaceutical wastewater.
Textile wastewater may be another area where these composite materials
may find application. Textile effluents may contain dyes, heavy metals, and
other pollutants that can be challenging to remove. The composite materials may
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be able to address multiple contaminants simultaneously, potentially improving
the overall treatment efficiency.
In some implementations, the composite materials may be used to treat
coke oven effluent. This type of wastewater may contain high levels of phenols,
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ammonia, and other pollutants. The composite materials may be effective in
reducing the concentrations of these contaminants, potentially making the water
suitable for reuse or safe discharge.
The effectiveness of the composite materials in these water treatment
applications may vary depending on factors such as the specific composition of
the composite, the nature and concentration of the contaminants, and the
treatment conditions. In an embodiment of the invention, the treatment process
may involve multiple stages or combinations of different composite materials to
achieve optimal results.
The ability of these composite materials to address multiple contaminants
may make them particularly valuable in water treatment applications. By
potentially reducing levels of arsenic, fluoride, COD, and other pollutants, these
materials may contribute to improving water quality and addressing
environmental challenges associated with various types of wastewater.
In some implementations, Fig. 3 shows the process may be carried out in
a system (200) comprising specific units for each major step. A separation unit
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(210) may handle the initial separation of metallic lumps from residual powder.
A treatment unit (220) may be used for mixing the metallic lumps with
aluminium nanoparticles. An inductive heating unit (230) may facilitate the
recovery of metallic aluminium from the treated lumps. Finally, a conversion
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unit (240) may process the residual powder into composite materials.
The integration of these units into a cohesive system may allow for
efficient material flow and energy use. For example, heat generated in the
inductive heating unit may potentially be recovered and used in other parts of
the process, such as drying the washed residual powder.
The system may also incorporate feedback loops to optimize
performance. For instance, data from the inductive heating unit regarding
recovery efficiency may be used to adjust parameters in the treatment unit,
potentially improving overall aluminium recovery.
By processing both the metallic lumps and the residual powder, this
approach may maximize resource recovery from the aluminium dross. The
production of value-added materials from the residual powder may offset the
costs associated with dross processing, potentially improving the economic
viability of the system.
Moreover, by finding productive uses for all components of the
aluminium dross, this process may help to reduce the volume of material sent to
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landfills. This reduction in waste may contribute to environmental protection
efforts and may align with principles of circular economy.
The water treatment applications of the composite materials produced
from the residual powder may provide additional environmental benefits. By
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potentially reducing levels of contaminants such as arsenic, fluoride, and
chemical oxygen demand in wastewater, these materials may contribute to
improving water quality in various industrial and municipal settings.
In another embodiment of the invention, the system may be designed with
flexibility to handle variations in dross composition. This adaptability may allow
for efficient processing of dross from different sources or with varying
characteristics, potentially expanding the applicability of the system.
The integration of multiple processing steps into a single system may also
offer logistical advantages. By potentially reducing the need for transportation
between separate facilities, this approach may lower overall energy consumption
and associated emissions.
The invention is further illustrated by the following examples without
limiting the scope of claims to these examples.
Example 1: Synthesis of Alumina/Copper composite (ALD 1)
Mixed alumina/copper nanocomposite was synthesized by combustion
method. Aluminium dross powder and copper (0.03-100 µM) at ratio 1:0.1 to
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1:1 was placed in a crucible (graphite, iron, aluminium, silica) and heated to
400-1000oC in muffle furnace or inductive furnace for 15-60 minutes to obtain
the desired mixed composite sample in quantitative yields. The loss of ignition
was 7-12%.
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Example 2: Synthesis of Alumina/Copper oxide composite (ALD 2)
Mixed alumina/copper oxide nanocomposite was synthesized by
combustion method. Aluminium dross powder and copper oxide (0.03-100 µM)
at ratio 1:0.1 to 1:1 was placed in a crucible (graphite, iron, aluminium, silica)
and heated to 400-1000°C in muffle furnace or inductive furnace for 15-60
minutes to obtain the desired mixed composite sample in quantitative yields. The
loss of ignition was 8-15%.
Example 3: Synthesis of Alumina/Copper-zinc composite (ALD 3)
Mixed alumina/copper-zinc nanocomposite was synthesized by
combustion method. Aluminium dross powder and copper-zinc alloy (50-100
nm) at ratio 1:0.1 to 1:1 was placed in a crucible (graphite, iron, aluminium,
silica) and heated to 400-1000°C in muffle furnace or inductive furnace for 15
60 minutes to obtain the desired mixed composite sample in quantitative yields.
The loss of ignition was 10-18%.
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Example 4: Synthesis of Alumina/Copper nickel composite (ALD 4)
Mixed alumina/copper-nickel nanocomposite was synthesized by
combustion method. Aluminium dross powder and copper zinc alloy (50-100
nm) at ratio 1:0.1 to 1:1 was placed in a crucible (graphite, iron, aluminium,
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silica) and heated to 400-1000°C in muffle furnace or inductive furnace for 15
60 minutes to obtain the desired mixed composite sample in quantitative yields.
The loss of ignition was 8-18%.
Example 5: Synthesis of Alumina/iron nickel composite (ALD 5)
Mixed alumina/iron-nickel nanocomposite was synthesized by
combustion method. Aluminium dross powder and iron-nickel powder (0.03
100 µM) at ratio 1:0.1 to 1:1 was placed in a crucible (graphite, iron, aluminium,
silica) and heated to 400-1000°C in muffle furnace or inductive furnace for 15
60 minutes to obtain the desired mixed composite sample in quantitative yields.
The loss of ignition was 10-15%.
Example 6: Synthesis of Alumina/iron oxide nickel composite (ALD 6)
Mixed alumina/iron oxide nanocomposite was synthesized by
combustion method. Aluminium dross powder and iron oxide (0.03-100 µM) at
ratio 1:0.1 to 1:1 was placed in a crucible (graphite, iron, aluminium, silica) and
heated to 400-1000°C in muffle furnace or inductive furnace for 15-60 minutes
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to obtain the desired mixed composite sample in quantitative yields. The loss of
ignition was 6-10%.
Example 7: Synthesis of Alumina/zinc composite (ALD 7)
Mixed alumina/zinc nanocomposite was synthesized by combustion
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method. Aluminium dross powder and zinc (0.03-100 µM) at ratio 1:0.1 to 1:1
was placed in a crucible (graphite, iron, aluminium, silica) and heated to 400
1000°C in muffle furnace or inductive furnace for 15-60 minutes to obtain the
desired mixed composite sample in quantitative yields. The loss of ignition was
10-15%.
Example 8: Synthesis of Alumina/zinc oxide composite (ALD 8)
Mixed alumina/zinc oxide nanocomposite was synthesized by
combustion method. Aluminium dross powder and zinc oxide (0.03-100 µM) at
ratio 1:0.1 to 1:1 was placed in a crucible (graphite, iron, aluminium, silica) and
heated to 400-1000°C in muffle furnace or inductive furnace for 15-60 minutes
to obtain the desired mixed composite sample in quantitative yields. The loss of
ignition was 8-12%.
Example 9: Synthesis of Alumina/red mud composite (ALD 9)
Mixed alumina/red mud nanocomposite was synthesized by combustion
method. Aluminium dross powder and redmud powder at ratio 1:0.1 to 1:1 was
placed in a crucible (graphite, iron, aluminium, silica) and heated to 400-1000°C
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in muffle furnace or inductive furnace for 15-60 minutes to obtain the desired
mixed composite sample in quantitative yields. The loss of ignition was 12-16%.
Example 10: Synthesis of Alumina/chitosan mixed composite (ALD 10)
To the 1% aq. Acetic acid (100 mL) was added to chitosan (1.0 g) and
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heated to 60°C until chitosan was completely dissolved. To this solution 0.5 g
of aluminium dross powder was added with continuous stirring. Sodium
hydroxide (2.5 N, 100 mL) was added and waited for 3 h. After 3 h, the solid
was filtered and dried in a hot air oven to obtain the desired mixed
nanocomposite sample 1.32 g (88%). The material was used for fluoride
removed by using 2 and ppm which was reduced to 0 ppm.
Example 11: Synthesis of Alumina/alginate mixed composite (ALD 11)
To the 1% aq. Acetic acid (100 mL) was added sodium alginate (1.0 g)
and heated to 60oC until chitosan was completely dissolved. To this solution 0.5
g of aluminium dross powder was added with continuous stirring. Sodium
hydroxide (2.5 N, 100 mL) was added and waited for 3 h. After 3 h, the solid
was filtered and dried in hot air oven to obtain the desired mixed nanocomposite
sample (1.4 g, 93%). The material was used for fluoride removed by using 2 and
ppm which was reduced to 0 ppm.
Table 4 shows the aluminium purity and efficiency data for the given
Zero-Waste Process for Making Value-Added Products
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Parameter
Zero-Waste Process
(Proposed Method)
Conventional Aluminium
Dross Processing
Purity of
Recovered
Aluminium 95–99%
50–65% (Impurities remain
due to incomplete separation)
Recovery
Efficiency 70–90%
50–60% (Losses due to
oxidation and incomplete metal
separation)
Residual
Dross
Utilization
Nearly 100% (Converted
into value-added products)
50–70% Waste (significant
portion discarded or landfilled)
Energy
Efficiency
High (Inductive/muffle
furnace reduces energy
loss)
Medium to Low (Traditional
smelting requires high energy
input)
Environmenta
l Impact
Low (Zero-waste, minimal
landfill disposal)
High (Dross waste disposal
leads to environmental
pollution)
Moderate
Process
(Multi-step
process but optimized for
Complexity
Use
Nanoparticles
full recovery)
of
Yes (Enhances recovery
and purity)
Lower (Simpler process but
results in lower recovery and
more waste)
No (Standard melting and
separation techniques used)
The Zero-Waste Process achieves 95–99% aluminium purity, which is
superior to the 50–65% range of conventional methods. This improvement is
attributed to the inclusion of aluminium nanoparticles during the melting
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process, which enhances the removal of impurities and prevents oxidation losses
during recovery. The proposed process ensures a 70–90% recovery efficiency,
significantly outperforming the conventional methods, which recover only 50
60% of aluminium from dross. The multi-step crushing, separation, and
nanoparticle-assisted melting in the Zero-Waste Process optimize the extraction
of metallic aluminium, making it more effective than traditional approaches that
often result in significant material losses. A defining feature of the Zero-Waste
Process is its ability to utilize nearly 100% of residual dross by converting it into
value-added products, such as composites or reusable materials. In contrast,
conventional recycling methods discard 30–50% of the residual dross, which
typically ends up in landfills, contributing to environmental pollution. This zero
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waste approach aligns with the principles of sustainability and the circular
economy. The Zero-Waste Process employs inductive or muffle furnaces, which
offer controlled heating and reduce energy losses compared to the high-energy
traditional smelting methods used in conventional recycling. This not only
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reduces operating costs but also makes the process more environmentally
friendly by lowering the overall energy footprint. The proposed process has a
low environmental impact due to its zero-waste design and efficient recovery of
aluminium and residual materials. On the other hand, conventional methods
generate substantial waste, with a significant portion of dross discarded as non
recyclable material, leading to increased landfill usage and environmental
degradation. The incorporation of aluminium nanoparticles in the melting stage
is a key innovation in the Zero-Waste Process. This unique feature enhances
both purity and recovery efficiency, providing a technical advantage over
traditional recycling methods, which rely solely on mechanical separation and
standard melting techniques.
In summary, the interaction of various elements in this process may create
a synergistic system for aluminium dross processing. By recovering metallic
aluminium and producing value-added materials from residual powder, this
approach may offer a comprehensive solution to challenges associated with
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aluminium dross management while potentially providing environmental and
economic benefits.
A number of implementations have been described. Nevertheless, it will
be understood that various modifications may be made without departing from
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the spirit and scope of the invention. Accordingly, other implementations are
within the scope of the following claims. , Claims:We Claim:
1.
A process for recovering aluminium and value-added products from
aluminium dross, comprising

separating of 220kg of metallic lumps from the 450kg of residual powder
of aluminium dross;
crushing the metallic lumps from the said step into fine particles;
mixing the crushed metallic lumps with various aluminium nanoparticles
and heating in an inductive furnace or muffle furnace to obtain 8.6kg of metallic
aluminium and 230kg of residual dross powder;
treating the obtained residual powder, washed with water, and mixed with
metallic material, and heating in an inductive furnace or muffle furnace to form
value-added products.
2.
The process as claimed in claim 1, wherein the value-added products are
in the form of composites.
3.
The process as claimed in claim 1, wherein the addition of aluminium
nanoparticles during the melting process to achieve the 95-99% purity and 70
90%efficiency of metallic aluminium recovery.
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4.
The process as claimed in claim 1, wherein the residual dross powder was
washed with water to remove the soluble salts at room temperature to 100°C in
order to avoid any in-situ product.
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5.
The process as claimed in claim 1, wherein the combination of multi
stage dross treatment, use of nanoparticles, sequential heating process, and
conversion of waste into value-added products to enhance the aluminium
recovery and achieve ~100% of value-added products.
6.
The process as claimed in claim 1, wherein the aluminium nanoparticles
size varies from 100 nm-1000nm and preferably 100-300 nm.
7.
The process as claimed in claim 1, wherein the heating at a temperature
ranges from 700-1200oC using an inductive furnace or muffle furnace, and the
preferable temperature 900-1100oC.
8.
The process as claimed in claim 1, wherein the crucibles were selected
from iron, stainless steel, graphite, quartz and ceramic for inductive furnace
heating.
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9.
The process as claimed in claim 1, wherein the inductive heating with the
voltage ranges from 300V-450V and frequency 400-1500Hz and wherein the
preferred voltage is 380V, and the frequency 900-1200Hz industrial electricity.
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10.
The process as claimed in claim 1, wherein the composite comprising:
0.03-100µm of Aluminium dross powder and metallic material, wherein the
ratio is 1:0.1 to 1:1
11.
The process as claimed in claim 1, wherein the metallic material selected
from at least one of aluminium, copper, copper oxide, copper-nickel alloy,
copper-zinc alloy, iron, iron oxide, zinc, zinc oxide, chitosan, alginate, and red
mud.
12.
The process as claimed in claim 1, wherein the synthesis of
alumina/metallic material mixed composite, comprising:
adding 1% aq. Acetic acid (100 mL) to the metallic material (1.0 g) and
heated to 60°C until metallic material is completely dissolved to form a first
mixture solution;
adding 0.5 g of aluminium dross powder to the above first mixture
solution and continuously stirring to form a second mixture solution;
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adding sodium hydroxide (2.5 N, 100 mL) to the second mixture solution
and left to react for 3 hour;
filtering the solid after 3 hour and drying in a hot air oven to obtain the
desired mixed nanocomposite.
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13.
The process as claimed in claim 1, wherein the arsenic level is reduced
from 500-1000 ppb to 50-100 ppb and the fluoride level is reduced from 5 ppm
to 0.2 ppm in water using this composite material.
14.
The process as claimed in claim 1, wherein the chemical oxygen demand
level is reduced from 10-15K ppm to 5-6K ppm, when treated with dross
powder.
15.
A system (200) for processing aluminium dross, comprising:
a separation unit (210) for separating metallic lumps from residual
powder in aluminium dross;
a treatment unit (220) for mixing the metallic lumps with aluminium
nanoparticles;
an inductive heating unit (230) for heating the treated metallic lumps to
recover metallic aluminium;
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and a conversion unit (240) for processing the residual powder into
composite materials.