Laterite Nickel Slag Chlorination for Al-Sc Separation
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Solution Overview
Problem
Existing methods for extracting scandium from iron-aluminum slag in laterite nickel ore hydrometallurgy face challenges in separating scandium from aluminum due to their similar chemical properties, leading to reduced scandium recovery and product purity.
Innovation Solution
A method involving staged distillation with HCl gas streams at controlled temperatures to convert iron, aluminum, and scandium into their chloride salts, followed by leaching and precipitation treatments to achieve deep separation and high-purity products.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If acid-base leaching or water leaching after calcination is used to extract Sc from iron-aluminum slag, then the extraction process can be performed, but the separation of Al and Sc is difficult due to their similar chemical properties and high aluminum content, leading to reduced Sc recovery and product purity
Solution Approach 1:
The patent changes the chemical parameters by introducing HCl gas to create a chlorination environment, transforming the extraction mechanism from aqueous leaching to gas-phase chlorination followed by selective condensation. This parameter change enables effective separation of Al and Sc by exploiting differences in their chloride volatility and condensation temperatures, resolving the separation difficulty caused by similar chemical properties in traditional leaching methods
Solution Approach 2:
The patent utilizes phase transitions of metal chlorides through controlled temperature condensation. AlCl3 condenses at lower temperatures while ScCl3 requires higher temperatures for condensation. This phase transition-based separation method effectively divides Al and Sc into different product streams, achieving high purity products and resolving the contradiction between separation effectiveness and product purity
2Ease of manufacture
If traditional extraction or precipitation methods are used, then the process can be simplified, but most Sc will continue to enter the final aluminum or iron product, affecting the purity of aluminum or iron products and reducing the effective recovery of Sc
Solution Approach 1:
The patent segments the extraction process into distinct temperature zones: a first condensation zone for AlCl3 collection at lower temperatures and a second condensation zone for ScCl3 collection at higher temperatures. This segmentation allows selective recovery of different metal chlorides in sequence, ensuring high Sc recovery rate while maintaining process simplicity through systematic temperature control
3Measurement precision
If high-temperature distillation is used to separate Sc from Al, then separation effectiveness improves, but energy consumption increases
Solution Approach 1:
The patent employs periodic action through staged temperature increase: first condensing AlCl3 at lower temperatures, then increasing temperature to condense ScCl3. This staged approach avoids the need for continuous high-temperature operation, reducing overall energy consumption while maintaining high separation effectiveness through sequential temperature-controlled condensation
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
The method achieves high-purity iron, aluminum, and scandium products with improved recovery rates, along with the production of valuable by-products like scandium oxide and mixed hydroxide precipitate, while minimizing waste and energy consumption.
Implementation Method 1
introducing an HCl gas stream for a one-stage distillation at 185-290°C to obtain a one-stage distillation tail gas and a one-stage distillation residue
Implementation Method 2
introducing an HCl gas stream for a one-stage distillation at 185-290°C to obtain a one-stage distillation tail gas and a one-stage distillation residue
Implementation Method 3
condensing the one-stage distillation tail gas to obtain anhydrous AlCl3
Data Source
AI summary
A comprehensive utilization method for valuable elements in hydrometallurgical slag of laterite nickel ore, comprising the following steps: S1. placing an iron-aluminum slag produced by laterite nickel ore hydrometallurgy in a tube furnace, and introducing an HCl gas stream for a one-stage distillation at 185-290°° C. to obtain a one-stage distillation tail gas and a one-stage distillation residue; and condensing the one-stage distillation tail gas to obtain anhydrous AlCl3; S2. introducing an HCl gas stream to the one-stage distillation residue for a two-stage distillation at 320-500°° C. to obtain a two-stage distillation tail gas and a two-stage distillation residue; and condensing the two-stage distillation tail gas to obtain anhydrous FeCl3; S3. subjecting the two-stage distillation residue to a leaching treatment by using a leaching solution to obtain a leaching residue and a leaching solution; subjecting the leaching solution to a scandium precipitation treatment to obtain a scandium precipitate and a de-scandiumed liquid; S4. adjusting the pH value of the de-scandiumed liquid to obtain an MHP. The obtained aluminum, iron, and scandium products have high purity and high recovery.