Hydrochloric Acid Leaching of Nickel Oxide Ores
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Solution Overview
Problem
Conventional methods for extracting nickel and other base metals from oxide ores, such as laterites, face challenges including high operational and capital costs, excessive acid consumption, impurity extraction, and complex solid-liquid separation, particularly due to high magnesium content in ferruginous ores.
Innovation Solution
A process involving the in-situ generation of hydrochloric acid by agglomerating ferric or ferrous chloride with ore and subjecting it to selective hydrolysis, which forms metal chlorides that are soluble in water, eliminating the need for iron and aluminum removal stages and reducing acid consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional acid leaching methods are used to extract base metals from oxide ores, then metal recovery is achieved, but acid consumption becomes excessively high due to the need to leach both iron and magnesium
Solution Approach 1:
The leaching process is segmented into two distinct stages: first, selective leaching of base metals using hydrochloric acid; second, selective leaching of iron and magnesium using sulfuric acid. This segmentation allows each acid to target specific metals, preventing excessive consumption of a single acid type while maintaining effective metal recovery.
Solution Approach 2:
Different acids are applied to different target metals based on their specific chemical properties. Hydrochloric acid is used locally for base metal extraction, while sulfuric acid is applied specifically for iron and magnesium removal. This localized approach optimizes acid usage efficiency and reduces overall acid consumption compared to using a single acid for all metal extractions.
2Productivity
If high pressure acid leaching is used to handle ferruginous ores, then iron hydrolysis is achieved, but magnesium removal remains problematic and operational costs increase
Solution Approach 1:
The process separates magnesium removal from the high-pressure acid leaching stage by using a subsequent sulfuric acid leaching stage specifically for magnesium and iron removal. This segmentation allows the HPAL stage to focus on base metal recovery while magnesium is addressed in a dedicated later stage, improving operational ease.
Solution Approach 2:
The process changes the chemical parameters by introducing sulfuric acid after the initial HPAL stage, creating different chemical conditions that favor magnesium removal. This parameter change enables effective magnesium extraction without requiring continued high-pressure conditions, simplifying operational complexity.
3Productivity
If conventional leaching processes are used to extract nickel from laterites, then metal extraction is achieved, but the number and complexity of unit operations increases capital and operational costs
Solution Approach 1:
Multiple leaching functions are merged into a coordinated two-stage process where hydrochloric acid leaching is followed by sulfuric acid leaching. This merging of functions into a unified process sequence reduces the number of separate unit operations compared to using multiple independent leaching systems, thereby reducing capital and operational costs while maintaining effective metal extraction.
4Productivity
If excess acid is used to achieve high extraction of payable metals, then metal recovery increases, but operational costs due to acid consumption increase
Solution Approach 1:
Different acids are applied to different target metals based on their specific chemical properties. Hydrochloric acid is used locally for base metal extraction, while sulfuric acid is applied specifically for iron and magnesium removal. This localized approach optimizes acid usage efficiency and reduces overall acid consumption compared to using a single acid for all metal extractions.
Solution Approach 2:
The process changes the chemical parameters by introducing sulfuric acid after the initial HPAL stage, creating different chemical conditions that favor magnesium removal. This parameter change enables effective magnesium extraction without requiring continued high-pressure conditions, simplifying operational complexity.
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 reduces capital costs, simplifies equipment needs, minimizes corrosion issues, and enhances the extraction efficiency of base metals like nickel, cobalt, and copper while stabilizing magnesium and iron as oxides, facilitating easier purification and reducing effluent treatment costs.
Implementation Method 1
subjecting it to selective hydrolysis, which forms metal chlorides that are soluble in water
Data Source
AI summary
A method for recovering base metal values from oxide ore is provided, where the ore includes a first group metal selected from nickel, cobalt and copper. The method includes reducing ore particle size to suit the latter unit operation, favoring contact for the metal elements, contacting the ore with ferric or ferrous chloride, hydrated or anhydrous, to produce a mix of ore and iron (II or III) chloride subjecting the mixture of the ore and ferric or ferrous chloride to enough energy to decompose the chlorides into hydrochloric acid and a iron oxides from the second group, forming their respective chlorides, selectively dissolve the produced base metal chlorides, leaving the metal as oxides and in the solid state, and recovering the dissolved base metal values from aqueous solution.