Goethite Iron Removal in Hydrometallurgy
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Solution Overview
Problem
Current methods for removing iron from hydrometallurgical solutions consume large amounts of reducing agents and oxidants, leading to inefficient iron removal and increased operational costs, with challenges in solid-liquid separation and recovery of valuable metals.
Innovation Solution
A method involving the controlled addition of an iron-containing solution to a reactor with pH and temperature management, using a homogenizing distributor to convert ferric iron to goethite without the need for ferric iron-ferrous iron conversion, utilizing a neutralizer like limestone or sodium hydroxide to maintain pH between 2.5 and 4, and oxidants like air or oxygen when necessary, facilitating easy solid-liquid separation and reducing reagent consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If reducing agent and oxidizing agent are added to convert ferric iron to ferrous iron and then back to ferric iron for precipitation, then iron removal is achieved, but large amounts of reagents are consumed and reducing slag is generated
Solution Approach 1:
The patent extracts and eliminates the unnecessary intermediate conversion steps (ferric iron to ferrous iron and back) from the iron removal process. By directly precipitating ferric iron as goethite without using reducing agents and oxidizing agents for conversion, the method removes the harmful element (excessive reagent consumption) while preserving the core function (iron removal).
Solution Approach 2:
The patent converts the previously harmful effect of direct ferric iron precipitation (colloidal form difficult to separate) into a beneficial outcome by controlling precipitation conditions (pH 2.5-4, temperature 65-100°C) to form goethite with excellent sedimentation and filtering performances, eliminating the need for reagent-based conversion while achieving better solid-liquid separation.
2Reliability
If direct neutralization is used for hydrolytic precipitation of ferric iron, then iron removal is achieved, but the main product is colloidal iron hydroxide that is difficult to separate from solution
Solution Approach 1:
The patent changes the precipitation parameters from simple neutralization (pH control only) to controlled hydrolysis conditions (pH 2.5-4, temperature 65-100°C). This parameter modification transforms the precipitation product from colloidal iron hydroxide to crystalline goethite, which has superior settleability and filterability, thereby resolving the solid-liquid separation difficulty.
Solution Approach 2:
The patent induces a phase transition in the iron precipitation process by controlling conditions to form crystalline goethite instead of amorphous colloidal hydroxide. This phase change from colloidal to crystalline structure fundamentally improves the physical properties of the precipitate, making it easily separable through sedimentation and filtration.
3Ease of operation
If thickener is used for solid-liquid separation of iron hydroxide precipitation, then separation is achieved, but underflow concentration is less than 20% and valuable metals are entrained in underflow ore pulp
Solution Approach 1:
The patent changes the precipitate formation parameters to produce goethite with superior settling characteristics. The controlled pH (2.5-4) and temperature (65-100°C) conditions create precipitates with better density and settleability, enabling the thickener to achieve underflow concentrations above 35% while minimizing valuable metal entrainment.
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 approach achieves high iron removal rates (90-99%) with improved solid-liquid separation, increasing the underflow concentration of the thickener to above 35%, reducing valuable metal entrainment and enhancing the recovery rate of metals except iron, while minimizing reagent use and operational costs.
Implementation Method 1
controlling concentration of the ferric iron in the reactor below 1 g/L, controlling pH of the solution in the reactor to be 2.5 ̃4, the temperature to be 65 ̃100° C., and the reaction duration to be 1 ̃3 hours, performing solid-liquid separation for the solution after reaction, and removing the iron in the iron-containing solution in hydrometallurgy in the form of goethite
Implementation Method 2
controlling pH of the solution in the reactor to be 2.5 ̃4 is achieved by adding neutralizer to the reactor through a second homogenizing distributor. The neutralizer is one or more selected from a group consisting of limestone, lime, magnesium oxide, zinc oxide and sodium hydroxide
Implementation Method 3
when the iron-containing solution in hydrometallurgy contains ferrous iron, oxidant is added to the reactor to oxidize ferrous iron to ferric iron; when the iron-containing solution in hydrometallurgy does not contain ferrous iron, it is unnecessary to add oxidant to the reactor. The oxidant is air or oxygen
Implementation Method 4
adding the iron-containing solution in hydrometallurgy into a reactor through a first homogenizing distributor. The first homogenizing distributor is a uniform dispersing device
Implementation Method 5
performing solid-liquid separation for the solution after reaction. a thickener for removing the goethite generated in the reactor through solid liquid separation
Data Source
AI summary
The present disclosure discloses a method and device for removing iron in an iron-containing solution in hydrometallurgy. This method comprises the steps of: adding an iron-containing solution in hydrometallurgy into a reactor through a first homogenizing distributor, controlling concentration of the ferric iron in the reactor below 1 g/L, controlling pH of the solution in the reactor to be 2.5˜4, the temperature to be 65˜100° C., and the reaction duration to be 1˜3 hours, performing solid-liquid separation for the solution after reaction, and removing the iron in the iron-containing solution in hydrometallurgy in the form of goethite.