Goethite Red Mud Flocculation via Acrylic Polymer
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Solution Overview
Problem
Conventional flocculants are ineffective for separating red mud from alumina-containing ores with high goethite content, particularly those from Indonesia, leading to poor settling rates and economic inefficiencies in the Bayer process.
Innovation Solution
A washing method involving the use of a flocculant with a polymer containing a repeating unit derived from (meth)acrylic acid or its salt, free from vinylhydroxamic acid, is applied to red mud with a goethite to hematite mass ratio of 60/40 or more, limiting aluminum concentration in the suspension to 95 g/L or less, and adjusting alkali concentration and polymer anionization degree to enhance settling and concentration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional polymer flocculants (sodium acrylate, copolymer of sodium acrylate and amide acrylate) are used for red mud separation, then settling rate is improved for hematite-containing ores, but they are ineffective for goethite-containing ores (goethite/hematite ratio ≥ 60/40)
Solution Approach 1:
The patent changes the chemical composition parameters of the flocculant by specifying a polymer with repeating units derived from (meth)acrylic acid or its salts, having specific anionization degrees (40-100 mole %) depending on aluminum concentration. This parameter change makes the flocculant effective for goethite-containing red mud where conventional flocculants fail, resolving the contradiction between productivity and reliability for different ore types.
2Productivity
If aluminum concentration in suspension is high, then alumina extraction efficiency is improved, but flocculant effectiveness is reduced for goethite-containing red mud
Solution Approach 1:
The patent establishes specific parameter ranges: aluminum concentration ≤ 95 g/L and flocculant anionization degree between 40-100 mole % (selected based on aluminum concentration). These parameter changes allow maintaining high alumina extraction while ensuring flocculant effectiveness for goethite-containing ores, resolving the contradiction between extraction efficiency and settling ease.
3Productivity
If flocculant with vinylhydroxamic acid repeating units is used, then settling is promoted in some cases, but the flocculant structure becomes more complex and costly
Solution Approach 1:
The patent extracts and eliminates the vinylhydroxamic acid repeating unit from the flocculant structure, specifying instead a polymer with repeating units derived from (meth)acrylic acid or its salts. This simplification maintains or improves settling promotion effectiveness while reducing structural complexity and cost, resolving the contradiction between productivity and device complexity.
4Adaptability or versatility
If red mud with high goethite content is separated using conventional methods, then processing of Indonesian ores is enabled, but settling rate and concentration level remain poor
Solution Approach 1:
The patent changes the flocculant's chemical parameters (polymer type with (meth)acrylic acid derivatives, anionization degree 40-100 mole %) to achieve effectiveness across different ore types including high-goethite Indonesian ores. This resolves the contradiction between adaptability to various ores and maintaining high settling rates.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method promotes high-level solid concentration and stability of red mud, overcoming the inefficiencies of conventional methods and achieving rapid, economical separation.
Implementation Method 1
adding a flocculant to the suspension, wherein the flocculant comprises a polymer having a repeating unit derived from (meth)acrylic acid or a salt thereof
Implementation Method 2
settling and separating the red mud so as to wash the red mud
Data Source
AI summary
A washing method of red mud that is produced when an alumina-containing ore having a goethite to hematite mass ratio of 60/40 (goethite/hematite) or more in the iron component thereof is heat-treated with an alkaline solution at a temperature of 110° C. to 160° C. to obtain an aluminate liquor, including: mixing the red mud with a diluting fluid to obtain suspension that has an aluminum concentration of 95 g/L or less in terms of Al2O3; adding a flocculant to the suspension, wherein, the flocculant includes a polymer having a repeating unit derived from (meth)acrylic acid or a salt thereof and being substantially free from a repeating unit derived from vinylhydroxamic acid compound or a salt thereof; and settling and separating the red mud so as to wash the red mud.