Acid-Resistant Cement Binder for Copper Heap Leaching
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Solution Overview
Problem
Copper heap leaching is limited by poor permeability and fines segregation in ores, leading to inadequate metal recoveries and longer leach times, with existing binders being ineffective in acidic media, particularly for copper ores.
Innovation Solution
A modified acid-proof cement binder, formed by adding supplementary cementitious materials like fly ash, ground iron blast furnace slag, silica fume, and sodium silicate to ordinary Portland cement, is used to agglomerate low-permeability ores, enhancing strength and acid resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional binders (cement, lime, molasses) are used in acid heap leaching, then agglomeration of fines can be achieved, but the binders are ineffective because they break down in acidic medium or lack acid resistance
Solution Approach 1:
The patent uses composite materials by combining ordinary Portland cement with supplementary cementitious materials (fly ash, ground granulated blast furnace slag, silica fume, natural pozzolans) to create an acid-resistant binder composite. This composite maintains structural integrity in acidic leaching environments while providing effective agglomeration of ore fines, resolving the contradiction between binder effectiveness and acid resistance.
Solution Approach 2:
The patent changes the chemical composition parameters of the binder by incorporating SCMs that modify the cement's reactivity and acid resistance properties. The addition of these materials alters the binder's chemical structure to withstand acidic conditions, transforming an ineffective conventional binder into an effective acid-resistant binder.
2Reliability
If ore with high clay content and poor permeability is used for heap leaching, then metal recovery can be improved, but the hydrodynamic performance deteriorates due to fines segregation and channeling
Solution Approach 1:
The patent applies preliminary action by performing agglomeration before heap leaching. The acid-resistant binder is mixed with ore fines and larger particles in advance to form uniform agglomerates with controlled porosity and strength. This pre-treatment prevents fines segregation and channeling during leaching, ensuring both high metal recovery and maintained productivity.
Solution Approach 2:
The patent applies local quality by creating agglomerates with specific local properties - the binder concentrates at particle contact points to form strong bonds, while the overall agglomerate structure maintains appropriate porosity for fluid flow. This localized binding approach improves metal recovery without compromising leaching productivity.
3Productivity
If screening out fines is implemented to improve permeability, then flow paths can be improved, but significant metal losses occur due to removal of fine ore particles containing valuable metal
Solution Approach 1:
The patent applies the taking out principle by extracting the problematic property (fines segregation and poor permeability) through chemical binding rather than physical removal. The acid-resistant binder selectively binds fines to larger particles, extracting the permeability problem from the ore feed without removing the valuable fine particles themselves, thus avoiding metal loss while improving flow characteristics.
4Reliability
If split circuit comprising heap and tank leaching is employed to handle fines, then metal recovery can be improved, but device complexity and operating costs increase
Solution Approach 1:
The patent applies universality by creating a single heap leaching system that can effectively process both coarse and fine ore particles. The acid-resistant binder enables the heap leach circuit to universally handle ores with varying fine content (up to 14% or more) without requiring separate processing circuits, thereby simplifying the overall system while maintaining high metal recovery.
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 binder improves permeability and metal recovery in copper heap leaching, allowing for faster leaching kinetics and higher copper dissolution rates, reducing slumping and net acid consumption, and increasing revenue by enabling efficient processing of previously uneconomical ores.
Implementation Method 1
The abovementioned SCMs (fly ash, furnace slag, silica fume, volcanic ash, volcanic rock, metakaolin and sodium silicate) contain pozzolanic properties, whereby calcium is consumed to produce additional calcium silicate hydrate (C—S—H in cement chem notation) and calcium aluminate hydrate (C-A-H) reaction products to replace calcium hydroxide (C—H) bonds, thereby increasing the strength and acid resistance of the agglomerates.
Data Source
AI summary
A binder for use in leaching a heap of a low-permeability ore containing at least one of the following: copper ore, copper/cobalt ore, nickel laterite ore and uranium ore, wherein the binder comprises an acid-proof cement formed by modifying ordinary Portland cement (OPC) with a supplementary cementitious material (SCM).