Selective Copper Removal from Molybdenite via Pressurized Oxidative Leaching
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Solution Overview
Problem
Current hydrometallurgical processes for cleaning molybdenite concentrates are costly and inefficient, often using corrosive chlorinated compounds and requiring high energy, and fail to effectively remove copper sulfides without dissolving molybdenum or rhenium, leading to impurities that decrease roasting productivity and increase furnace maintenance.
Innovation Solution
A pressurized leaching process using sulfuric acid and oxygen to selectively oxidize copper sulfides and other impurities in an autoclave, generating sulfuric acid in situ, which allows for the removal of copper and other impurities while preserving molybdenum and rhenium, under controlled oxygen overpressure and temperature conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional chloride-based leaching is used to remove copper from molybdenite concentrate, then copper removal efficiency is improved, but operating costs and investment costs increase significantly
Solution Approach 1:
The patent replaces expensive, corrosive chloride-based leaching agents with a cheaper, environmentally friendly system using sulfuric acid and oxygen. The sulfuric acid can be generated in-situ through oxidation of sulfide minerals, eliminating the need for expensive external chemical inputs while achieving effective copper removal.
Solution Approach 2:
The patent changes the chemical parameters of the leaching system by using oxygen and sulfuric acid instead of chloride compounds. This parameter change transforms the leaching mechanism from chloride-complexation to oxidation-based copper dissolution, reducing both operational and capital costs while maintaining effectiveness.
2Manufacturing precision
If more flotation stages are used to reduce copper content in molybdenite concentrate, then concentrate quality is improved, but molybdenum recovery decreases
Solution Approach 1:
The patent applies preliminary chemical cleaning (oxidative leaching) to the molybdenite concentrate before final processing. This preliminary action removes copper and other impurities through controlled oxidation, allowing the concentrate to meet quality specifications without requiring excessive flotation stages that would compromise molybdenum recovery.
3Loss of substance
If dirty concentrate is processed without cleaning to increase recovery, then molybdenum recovery is improved, but roasting productivity decreases due to impurity formation
Solution Approach 1:
The patent employs a self-service cleaning mechanism where oxygen and moisture in the system naturally oxidize copper sulfides and other impurities in the concentrate. This self-cleaning action occurs during storage or before roasting, removing harmful impurities that would otherwise form low-melting-point molybdates and reduce roasting productivity, without requiring additional processing steps.
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 process efficiently produces a clean molybdenum concentrate with low copper content, suitable for roasting, increasing production capacity and enabling the recovery of rhenium, without the need for corrosive reagents and with reduced energy costs.
Implementation Method 1
leaching the first pulp inside a pressure reactor, in a pressurized leaching stage at an oxidizing atmosphere, with an oxygen-bearing gas, at a leaching temperature between 110°C.-180°C. with a partial pressure for the oxidizing gas inside the reactor between 20-150 psig (0.1-1.0 MPa) to obtain a second pulp containing the clean molybdenite concentrate and a solution or mother liquor containing the copper compounds and other impurities in solution produced by the chemical reactions of the leaching stage
Implementation Method 2
mixing a concentrate of impure MoS2 with process water and/or a leaching solution that has been acidified with sulfuric acid to obtain a first pulp
Data Source
AI summary
Disclosed is a process for the selective removal of copper compounds, and other impurities with respect to molybdenum and rhenium, from concentrates of molybdenite (MoS2) with a copper content that is higher than 0.5% in dry weight.