DESC:*** Complete Specification ***

“Method to process bath of smelters to obtain non-hazardous fluxes”

Cross references to related applications: This complete specification is filed further to patent application No. 202331056638 filed on 24/02/2024 and the entire content of the provisional specification filed therewith is incorporated herein in its entirety by way of reference.

Field of the invention
This invention belongs to the aluminum smelting industry and relates generally to the processing the bath of smelters to obtain value-added fluxes, being fluorspar-rich and fluorspar non-leachable fluxes in particular.

Definitions and interpretations
Before undertaking the detailed description of the invention below, it may be advantageous to set forth definitions of certain words or phrases used throughout this patent document: the terms “include” and “comprise,” as well as derivatives thereof, mean inclusion without limitation; the term “or” is inclusive, meaning and/or; the phrases “associated with” and “associated therewith,” as well as derivatives thereof, may mean to include, be included within, interconnect, with, contain, be contained within, connect to or with, couple to or with, be communicable with, cooperate with, interleave, juxtapose, be proximate to, be bound to or with, have, have a property of, or the like; and certain definitions are set forth for this document, as follows: -
(a) “Bath” shall refer to the typical composition
Ingredient %
Cryolite 50 to 80%
AlF2 10 to 15 %
Alumina 10 to 40%
NaF 0 to 10%

(b) The terms cover bath, tapped bath, skimmed bath, ACRM, SRSS shall be a analogous, and refer to Bath.
(c) “Cryolite” shall refer to sodium hexafluoroaluminate, represented by the formula Na3AlF6
(d) “Flourspar” shall refer to calcium fluoride, represented by the chemical formula CaF2

Background of the invention
Cryolite is known as one of the chief ores of Aluminum, others being Bauxite and Corundum. Commercially today, the Hall–Héroult process is the major industrial process for smelting aluminum, which involves dissolving alumina in molten cryolite followed by electrolysis of the molten salt bath.

Elemental aluminum cannot be produced by the electrolysis of an aqueous aluminum salts because hydronium ions readily oxidize elemental aluminum. Using molten aluminum salt could have been a solution, however impractical for electrolysis due to high melting points, for example the melting point of aluminum oxide is 2070oC. Hence, specially designed flux compositions are introduced to make the process possible to occur at reduced temperatures and hence amenable to electrolysis.

Cryolite is known to act as a solvent for the extraction of Aluminium from Bauxite, and therein helps to lower the melting point of Alumina to around 950oC, and also brings the Alumina in molten form and makes it a good conductor of electricity to allow its extraction via electrolytic reduction.

Flourspar is used as a flux in smelting to decrease the viscosity of slag. Also, Flourspar serves as a source of fluorine and fluorite. Metallurgical grade fluorite is a major source of hydrogen fluoride, a commodity chemical used to produce a wide range of materials. Fluorite has traditionally been used as a flux to lower the melting point of raw materials in steel production to aid the removal of impurities, and now also in the production of aluminum. Ceramic grade fluorite is used in the manufacture of opalescent glass, enamels, and cooking utensils. Acid grade fluorite is used to make hydrogen fluoride and hydrofluoric acid by reacting the fluorite with sulfuric acid.

Aluminum smelting processes often result in the generation of bath material, which can contain various impurities, including leachable fluorides. These impurities complicate the disposal and reuse of the bath material. Additionally, conventional methods of utilizing bath material do not offer significant improvements in terms of producing useful by-products, such as fluxes, in an economically viable or environmentally friendly manner.
Bath material, comprises the aforementioned ingredients as defined in the definitions section above, and is otherwise a waste material which is problematic to safely dispose off. Hence, it is desirable to have some means to process said bath material, in order to avoid traditional disposal, and at the same time, achieve resource reutilization from the same.

Fluorspar-rich fluxes are of significant industrial importance, especially in the metallurgy industry, for use in aluminum production and other related processes. Traditional fluxing materials, however, may not fully address the need for enhanced properties, particularly with regard to leachability of fluorides. As a result, a method that can selectively produce fluxes with distinct properties, such as those free from leachable fluorides, has become highly desirable.

Therefore from a commercial vantage, it would be highly desirable to have some means of producing non-hazardous fluxes from bath material. The applicant hereof has realized the potential of bath material from aluminum smelter units, which is otherwise a waste, to be a viable raw material for production of such fluxes, hence the present invention.

Technical issues on hand
Reutilizing aluminum smelter bath material presents several technical challenges due to its complex composition, including impurities, hazardous components, and the need for specialized processes to convert the waste into valuable by-products. Some of the key technical issues in the reutilization of aluminum smelter bath material include:
(a) Contamination and Toxicity: Aluminum smelter bath material often contains leachable fluorides, heavy metals (e.g., lead, cadmium), and other hazardous substances. These contaminants need to be carefully managed during reutilization processes to avoid environmental and health risks. Developing methods to remove or stabilize these toxins is a significant challenge.
(b) Complexity of Material Composition: Bath material can consist of a wide range of components, including spent flux, alumina, carbon, and metal oxides. Its complex and variable composition makes it difficult to standardize processes for effective reutilization. Different batches may require tailored treatments, complicating recycling operations.
(c) Low Value of Waste Product: The by-products from aluminum smelter bath material are not always of high commercial value. Fluorspar-rich flux or normal flux, for example, may require additional treatment to make them suitable for use in other industrial applications. The process of upgrading these by-products can be costly and resource-intensive.
(d) Energy-Intensive Recycling Processes: Reutilizing bath material often requires high-energy processes, such as heating, chemical treatments, or mechanical processing (e.g., crushing or screening). These processes can be energy-demanding, making the overall recycling process less cost-effective and potentially increasing the carbon footprint.
(e) Environmental Concerns: While reutilization is more environmentally friendly than disposal, improper treatment or incomplete reactions during the recycling process could still result in the release of harmful substances into the environment. For instance, if fluoride is not adequately removed or stabilized, it could leach out from the reused material and pose environmental risks.
(f) Inconsistent Quality of Recycled Materials: Due to variations in the chemical composition of aluminum smelter bath material, the quality of the reutilized product may fluctuate. This can affect the performance of recycled fluxes or other materials in subsequent industrial applications. Achieving consistency in the quality of the recycled product is essential for its broader industrial adoption.
(g) Lack of Established Reutilization Technologies: While there are some existing methods for recycling aluminum smelter bath material (e.g., flux production), the technology is not universally established or optimized. This means that many smelters may lack the technical expertise or infrastructure to effectively reuse bath material at scale.
(h) Cost-Effectiveness: The cost of processing aluminum smelter bath material for reutilization can sometimes exceed the economic value of the resulting by-products. The need for specialized treatments, transportation, storage, and handling can make the reutilization process less economically attractive without proper incentives, such as regulatory support or cost savings from avoided waste disposal.
(i) Health and Safety Risks: Workers involved in the handling and processing of bath material must be protected from exposure to harmful chemicals such as fluoride, which can cause respiratory and skin issues. Ensuring proper safety protocols and protective measures is crucial in any reutilization process to minimize health risks.
(j) Regulatory Compliance and Certification: Reutilizing aluminum smelter bath material may require compliance with environmental regulations, including those concerning the recycling of hazardous materials. This involves obtaining certifications and following stringent guidelines for material handling, treatment, and final product quality. Failure to meet regulatory standards can result in legal issues and operational disruptions.

In conclusion, the disposal of aluminum casting bath material involves significant technical challenges, including chemical contamination, environmental impact, regulatory compliance, and health and safety risks.

Therefore, overcoming the aforesaid issues requires further development in processing methods, safety protocols, and economic models to make the reutilization of smelter bath material more sustainable and profitable, which has thus served as the focus of directed research undertaken by the applicant named herein, in reaching the present invention.

Description of related art
While there were many common art references researched by the inventor(s) in ensuring that the present invention is novel, no patent prior art was identified as related to the present invention, and thus worthwhile to discuss in more detail in context of the present invention. State-of-art therefore, does not list a single effective solution embracing all considerations mentioned hereinabove, thus preserving an acute necessity-to-invent for the present inventor/s who, as result of focused research, has come up with novel solutions for resolving all needs once and for all. Work of the applicant/s hereof, specifically directed against the technical problems recited hereinabove and currently part of the public domain including earlier filed patent applications, is neither expressly nor impliedly admitted as prior art against the present disclosures.

A better understanding of the objects, advantages, features, properties and relationships of the present invention will be obtained from the following detailed description which sets forth an illustrative yet-preferred embodiment.

Objectives of the present invention
The present invention is identified in addressing at least all major deficiencies of art discussed in the foregoing section by effectively addressing the objectives stated under, of which:

It is a primary objective to provide an effective method for reutilization of bath material obtained from aluminium smelting units.

It is another objective further to the aforesaid objective(s) that said method results in valuable / value-added bulk products.

It is another objective further to the aforesaid objective(s) that said method optimizes a dross treatment process for maximum aluminium recovery, minimize waste generation, and reduce environmental impact.

It is another objective further to the aforesaid objective(s) that said method is safe and easy to implement, without undue requirement of capital, time or skilled resources.

The manner in which the above objectives are achieved, together with other objects and advantages which will become subsequently apparent, reside in the detailed description set forth below in reference to the accompanying drawings and furthermore specifically outlined in the independent claims. Other advantageous embodiments of the invention are specified in the dependent claims.

Brief description of drawings
The present invention is explained herein under with reference to the following drawings, in which:

FIGURE 1 is a flow chart illustrating the process flow / logic of the present invention.

The above drawings are illustrative of particular examples of the present invention but are not intended to limit the scope thereof. The drawings are not to scale (unless so stated) and are intended for use solely in conjunction with their explanations in the following detailed description.

Attention of the reader is now requested to the detailed description to follow which narrates a preferred embodiment of the present invention and such other ways in which principles of the invention may be employed without parting from the essence of the invention claimed herein.

Statement / Summary of the invention
The present invention provides a novel process for utilizing bath material obtained from aluminum smelter units to produce value-added fluxes, including a fluorspar-rich flux and a normal flux, by the following steps:
(a) Sizing of Bath Material
(b) Admixing with Hydrated Lime
(c) Holding for approximately 24 hours
(d) Screening of Resultant Material into fractions smaller than 1 mm and larger than 1 mm.

Detailed description
Principally, general purpose of the present invention is to assess disabilities and shortcomings inherent to known systems comprising state of the art and develop new systems incorporating all available advantages of known art and none of its disadvantages. Accordingly, the disclosures herein are directed towards

Implementation of the present invention, as per the preferred embodiment herein, is via the following sequence of steps:

Step 1. Receiving Bath Material:
Bath material is sourced from aluminum smelting units, which typically contains impurities including leachable fluorides.

Step 2. Sizing of Bath Material:
The bath material is subjected to a sizing operation, such as crushing, to obtain a particle size range of 0.01 mm to 30 mm.

Step 3. Admixing with Hydrated Lime:
The sized bath material is then admixed with 15% hydrated lime, where the hydrated lime has a particle size of 0 to 1 mm. The lime serves to facilitate the removal of leachable fluorides by reacting with them.

The admixture is held for approximately 24 hours to ensure complete reaction of the bath material with the leachable fluorides. This reaction time allows for proper interaction of the components to form a flux with reduced fluoride content.

Step 4. Screening of Resultant Material:
After the reaction period, the resultant material is screened using meshes / sieves or equivalent, into two fractions:
(a) Fraction A: Particles smaller than 1 mm, which form a fluorspar-rich flux with higher concentrations of fluoride.
(b) Fraction B: Particles larger than 1 mm, which form a normal flux free from leachable fluoride.

Variations of the aforesaid process may be implemented as per the following examples-

Example 1: Bath material from an aluminum smelting unit is crushed to a particle size of 5 mm. 15% hydrated lime (0 to 1 mm) is admixed, and the admixture is allowed to react for 24 hours. The resulting material is screened with help of physical screens / meshes into two fractions: one with particles under 1 mm, which forms a fluorspar-rich flux, and the other with particles over 1 mm, which forms a normal flux free from fluoride.

Example 2: A variation of the process is performed with bath material that has a larger particle size (up to 30 mm). After the admixture with hydrated lime and the 24-hour reaction period, the same screening process is performed, yielding two distinct flux types for different industrial applications.

As the reader shall appreciate, the present invention offers several distinct advantages over prior art, including:
(a) Enhanced Flux Quality: The process allows for the production of fluxes with targeted properties, such as fluorspar-rich flux and normal flux, which can be tailored for specific industrial applications.
(b) Environmental Benefits: By effectively reducing the leachable fluoride content in one of the flux fractions, the method addresses environmental concerns related to the disposal and reuse of bath material.
(c) Cost Efficiency: The process utilizes bath material from aluminum smelting units, a by-product that otherwise requires disposal, thus providing a cost-effective way to generate valuable industrial fluxes.

Industrial applicability
The present invention has been reduced to practice by the applicant named herein.
The method disclosed herein can be used in industrial applications where the need for fluxes with specific properties is critical, including aluminum production and other metal refining processes. The process allows for the economical reuse of bath material while providing high-quality fluxes that meet the requirements of the metallurgy industry.

The fluxes resulted from implementation of the present invention can be applied in various metallurgical processes, including aluminum production, where they serve as essential components for optimizing efficiency and performance.

As will be realized further, the present invention is capable of various other embodiments and that its several components and related details are capable of various alterations, all without departing from the basic concept of the present invention. Accordingly, the foregoing description will be regarded as illustrative in nature and not as restrictive in any form whatsoever. Modifications and variations of the system and apparatus described herein will be obvious to those skilled in the art. Such modifications and variations are intended to come within ambit of the present invention, which is limited only by the appended claims. ,CLAIMS:1] A method for producing value-added fluxes from bath material obtained from aluminum smelting units, comprising:
(a) Receiving bath material from smelter units;
(b) Sizing the bath material to a particle size of 0.01 mm to 30 mm;
(c) Admixing the bath material with 15% hydrated lime, wherein the hydrated lime has a particle size of 0 to 1 mm;
(d) Allowing the admixture to react for approximately 24 hours; and
(e) Screening the resultant material into two fractions:
? a fluorspar-rich flux with particles smaller than 1 mm; and
? a normal flux with particles larger than 1 mm.

2] The method for producing value-added fluxes from bath material obtained from aluminum smelting units as claimed in claim 1, wherein the normal flux has reduced leachable fluoride content.

3] The method for producing value-added fluxes from bath material obtained from aluminum smelting units as claimed in claim 1, wherein the fluorspar-rich flux contains higher concentrations of leachable fluorides.

4] The method for producing value-added fluxes from bath material obtained from aluminum smelting units as claimed in claim 1, wherein the process provides an environmentally friendly method for the reuse of bath material in aluminum smelting units.

5] The method for producing value-added fluxes from bath material obtained from aluminum smelting units as claimed in claim 1, wherein the fluxes produced are used in various metallurgical processes.