Copper Anode Slime Recovery via Vacuum Carbothermal Reduction
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Solution Overview
Problem
Current methods for treating copper anode slime are inefficient and environmentally harmful, as they involve complex processes, high waste production, and incomplete recovery of precious metals like gold and bismuth, with traditional pyrometallurgy and hydrometallurgy processes being time-consuming and generating significant slag and waste.
Innovation Solution
A recovery method involving sulfation roasting, oxygen stressing, acid leaching, and two-stage vacuum carbothermal reduction to efficiently extract selenium, tellurium, arsenic, lead, bismuth, gold, and silver from copper anode slime, reducing the emission of arsenic-containing soot and shortening the recovery cycle while improving the yield of valuable metals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional pyrometallurgy is used to remove base metals, then lead and bismuth can be separated from precious metals, but the process is time-consuming and produces a large amount of slag and soot
Solution Approach 1:
The patent changes the fundamental parameter of the process from oxidation-based pyrometallurgy to carbothermal reduction. By using carbon as a reducing agent at controlled temperatures (800-1000°C), the method achieves complete reduction of base metals to their metallic state, enabling efficient separation without the time-consuming oxidation steps and slag formation characteristic of traditional pyrometallurgy
Solution Approach 2:
The patent converts the harmful soot and slag byproducts of traditional pyrometallurgy into beneficial metallic products. Through carbothermal reduction, the carbon that would normally form harmful soot is instead used to reduce base metal oxides to metallic lead and bismuth, which can be efficiently separated from precious metals in the slag-free process
2Reliability
If traditional pyrometallurgy is used for metal recovery, then base metals can be removed, but a large amount of soot is produced
Solution Approach 1:
The patent converts the harmful soot byproduct into a beneficial reducing agent. Instead of carbon burning to form soot, the method uses controlled carbothermal reduction where carbon reacts with base metal oxides to form metallic lead and bismuth. This eliminates soot emission while achieving complete base metal removal
Solution Approach 2:
The patent creates an inert carbon-rich atmosphere through carbothermal reduction, preventing the formation of harmful soot. By maintaining a controlled reducing environment with carbon as the reducing agent, the process achieves base metal removal without the oxidative soot formation characteristic of traditional pyrometallurgy
3Productivity
If hydrometallurgy is used to leach gold, then gold can be extracted from anode slime, but the process is complicated and produces waste water and waste residues
Solution Approach 1:
The patent replaces the complex multi-step hydrometallurgical process with a simpler carbothermal reduction system. Instead of using chlorination, precipitation, and multiple filtration steps, the method uses direct carbon reduction to convert all metals to their metallic state, achieving gold extraction in a single simplified process stage
Solution Approach 2:
The patent extracts the essential function of gold recovery from the complex hydrometallurgical sequence by using direct carbothermal reduction. This single-step process simultaneously reduces all base metals and precious metals to their metallic forms, eliminating the need for multiple extraction and purification steps required by traditional hydrometallurgy
4Productivity
If traditional methods are used to recover precious metals, then gold and silver can be recovered, but the recovery cycle is long and yield is incomplete
Solution Approach 1:
The patent implements continuous carbothermal reduction that simultaneously processes all metal components in the anode slime. By maintaining continuous reduction of base metals to metallic forms, the process enables continuous separation and recovery of precious metals without the intermittent processing required by traditional methods, thereby shortening the recovery cycle and improving yield
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 effectively recovers valuable metals with high purity, reduces the amount of slag and waste, and simplifies the process, improving the environmental friendliness and efficiency of metal recovery by avoiding the emission of soot and shortening the recovery cycle.
Implementation Method 1
mixing copper anode slime with a concentrated sulfuric acid to obtain a first mixture, and subjecting the first mixture to sulfation roasting to obtain a selenium-containing soot and a calcine
Implementation Method 2
subjecting the selenium-containing soot to water absorption, first reduction, and drying in sequence to obtain a crude selenium
Implementation Method 3
subjecting the second mixture to oxygen stressing and acid leaching to obtain a copper-tellurium-containing leachate
Implementation Method 4
subjecting the second mixture to oxygen stressing and acid leaching to obtain a copper-tellurium-containing leachate
Implementation Method 5
subjecting the fourth mixture to low-temperature vacuum carbothermal reduction at 400° C. to 550° C. to obtain an arsenic oxide volatile and an arsenic-removed anode slime
Implementation Method 6
subjecting the gold-silver-antimony-rich residue to vacuum distillation to obtain a silver-antimony volatile and a gold-rich residue
Implementation Method 7
subjecting the silver-antimony volatile to refining by oxidation to obtain an antimony oxide volatile and a crude silver
Implementation Method 8
subjecting the crude silver to electrolysis to obtain silver; subjecting the gold powder to electrolysis to obtain gold
Implementation Method 9
subjecting the gold-rich residue to leaching gold by chlorination, third reduction, and electrolysis in sequence to obtain gold
Implementation Method 10
subjecting the gold-rich residue to leaching gold by chlorination, third reduction, and electrolysis in sequence to obtain gold
Data Source
AI summary
Provided is a recovery method for valuable metals in copper anode slime. By using the recovery method of the disclosure, selenium, copper, tellurium, arsenic, lead, bismuth, and precious metals gold and silver in the copper anode slime are recovered. The method adopts two-step vacuum carbothermal reduction to replace reduction smelting of anode slime and stepwise blowing of noble lead in the traditional pyrometallurgy, and avoids the emission of arsenic-containing soot in the traditional process. The recovered gold-rich residue contains almost no base metals such as lead, bismuth, antimony, and arsenic. After subjecting the gold-rich residue to leaching gold by chlorination and reduction, a gold powder could be obtained therefrom with a lower content of base metals than traditional processes. Therefore, the method greatly reduces the amount of produced slag, shortens the production cycle, and reduces the loss of precious metals in the slag.