Decopperized Anode Slime Leaching via Bottom Extraction Circulation
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Solution Overview
Problem
The leaching rate of gold in chlorination leaching of decopperized anode slime is low due to low oxidation-reduction potential and the formation of a slime pile at the tank bottom, which reduces contact between gold and the leaching solution, and increasing agitation speed does not sufficiently address this issue.
Innovation Solution
A method of hydrochloric acid oxidation leaching that combines slurry agitation with circulation, where the slurry is extracted from the bottom and returned to the top of the tank, maintaining an oxidation-reduction potential between 650 mV and 950 mV, and adjusting the slurry concentration and chlorine levels to enhance gold extraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If chlorination leaching is performed with traditional agitation methods, then the process is simple to operate, but the leaching rate of gold is low (90% or less) due to slime pile formation at the tank bottom
Solution Approach 1:
The agitation system is divided into multiple independent agitation devices positioned at different locations (bottom, middle, top) of the tank, each responsible for a specific zone. This segmentation ensures comprehensive slurry circulation throughout the entire tank volume, preventing slime pile formation at the bottom while maintaining operational simplicity through modular device configuration
Solution Approach 2:
The agitation devices operate with adjustable rotational speeds to dynamically adapt to different process conditions. The bottom agitation device operates at a higher speed to break up slime piles, while middle and top devices operate at lower speeds to maintain slurry circulation without excessive foam generation, optimizing the leaching rate dynamically
2Productivity
If the rotational speed of the agitation device is increased to eliminate slime pile, then the contact between gold and leaching solution improves, but the energy consumption increases and foam generation becomes excessive
Solution Approach 1:
The agitation function is segmented across three devices operating at different speeds. The bottom device operates at higher speed (800-1200 rpm) to eliminate slime piles with targeted energy input, while middle and top devices operate at lower speeds (400-800 rpm) to maintain circulation with minimal energy consumption, avoiding excessive foam generation
Solution Approach 2:
Different regions of the tank receive different agitation intensities tailored to local requirements. The bottom region receives high-intensity agitation to break up dense slime piles, while the middle and top regions receive moderate agitation sufficient for maintaining slurry suspension and circulation, optimizing energy distribution according to local needs
3Productivity
If multiple agitation devices are used to prevent slime pile formation, then the leaching rate improves to 95% or higher, but the device complexity increases
Solution Approach 1:
The agitation system is segmented into three functionally distinct devices positioned at bottom, middle, and top of the tank, each with optimized rotational speed for its specific zone. This segmentation achieves comprehensive slurry circulation and slime pile elimination, improving gold leaching rate to 95% or higher while maintaining reasonable device complexity through modular configuration
Solution Approach 2:
Each agitation device serves multiple functions: the bottom device breaks up slime piles and initiates circulation, the middle device maintains slurry suspension and promotes gas-liquid contact, and the top device ensures uniform distribution of leaching solution. This multi-functionality justifies the use of multiple devices by maximizing their utility in achieving the 95%+ leaching rate
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 significantly improves the leaching rate of gold to 95% or higher by ensuring consistent contact between gold and the leaching solution and preventing slime pile formation, outperforming traditional agitation methods.
Implementation Method 1
the oxidation-reduction potential of the slurry is low, and thus during the chlorination leaching, unreacted silver selenide, selenium, and the like in the slime act as a reducing agent with respect to gold
Implementation Method 2
hydrochloric acid oxidation leaching of the precious metal contained in decopperized anode slime
Data Source
AI summary
A method of leaching a precious metal contained in decopperized anode slime includes, agitating and circulating a slurry at the same time, in carrying out hydrochloric acid oxidation leaching of the precious metal contained in the decopperized anode slime by adding a hydrochloric acid and an oxidant to the slurry of the decopperized anode slime, wherein in the circulating, the slurry is extracted from a lower portion of a tank and supplied again into an upper portion of the tank.