Ammonium Complex Zinc Purification for Selective Pb-Cd-Cu Separation
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Solution Overview
Problem
Existing methods for purifying zinc electrolysis solutions fail to achieve high-purity copper, lead, and cadmium separation, leading to high consumption of zinc powder and low utilization rates, resulting in increased costs and impure lead slag with significant impurities.
Innovation Solution
An ammonium complex system-based method involving leaching, filtration, displacement reactions with metal ions, and electrolysis is employed to selectively separate and purify lead, zinc, and cadmium, with the purified metals being recycled for further use, reducing production costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If zinc powder is used to intermittently remove impurity elements such as copper, lead and cadmium, then the purification process can be carried out, but the utilization rate of zinc is less than 60% and the consumption of zinc powder is relatively large
Solution Approach 1:
The patent changes the chemical environment parameters by introducing ammonium chloride and controlling pH values (3.5-8) to create optimal conditions for selective displacement reactions. This allows for more efficient impurity removal with reduced zinc consumption by optimizing the chemical parameters of the purification system
Solution Approach 2:
The purification process is divided into multiple sequential stages: first removing copper with iron powder, then removing lead and cadmium with zinc powder in separate steps. This segmentation allows each displacement reaction to be optimized independently, improving overall zinc utilization efficiency while maintaining reliable purification
2Reliability
If zinc powder is used to remove impurity elements, then the leach solution can be purified, but the obtained lead slag has a content of 30-50% lead with low grade and lots of impurities
Solution Approach 1:
The patent separates the removal of different impurities into distinct stages: copper removal first, then lead and cadmium removal in a second stage. This segmentation allows for better control of each displacement reaction, resulting in higher purity lead slag with reduced impurity content compared to simultaneous removal methods
Solution Approach 2:
The patent uses ammonium chloride as an intermediary substance that facilitates the displacement reactions. The ammonium chloride system mediates the chemical environment to enhance the selectivity and efficiency of impurity removal, thereby improving the purity of the resulting lead slag
3Productivity
If conventional purification methods are used, then the leach solution can be treated, but the current efficiency is reduced and energy consumption is increased
Solution Approach 1:
The patent replaces energy-intensive mechanical or thermal purification methods with chemical displacement reactions. By using controlled chemical reactions (Fe + Cu²⁺, Zn + Pb²⁺/Cd²⁺) instead of high-energy processes, the system achieves effective purification with significantly reduced energy consumption while maintaining productivity
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 (>99.995% for zinc, >90% for lead, and >80% for cadmium) and integrates production and utilization, reducing zinc powder consumption and production costs.
Implementation Method 1
mixing the filtrate obtained in step (2) with metal lead to displace copper
Implementation Method 2
mixing the first separated liquid with metal cadmium to displace lead
Implementation Method 3
mixing the second separated liquid with metal zinc to displace cadmium
Implementation Method 4
electrolyzing the third separated liquid obtained in step (3) to obtain metal zinc
Data Source
AI summary
An ammonium complex system-based method for separating and purifying lead, zinc, cadmium, and copper, comprising the following steps: a zinc-containing raw material is leached using a leach solution to produce a leached solution; a filtrate and a filter residue are produced by filtration; the filtrate is mixed with metal lead to displace copper, undergoes a solid-liquid separation to produce a first separated liquid, is mixed with metal cadmium to displace lead, undergoes a solid-liquid separation to produce a second separated liquid, is mixed with metal zinc to displace cadmium, and undergoes a solid-liquid separation to produce a third separated liquid; and, the third separated liquid is electrolyzed to produce metal zinc, and an electrolytic solution is returned to the leaching step.