Rare Earth Leaching via Low-Temperature Phase Transformation
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Solution Overview
Problem
Conventional methods for processing Bayan Obo mixed type rare earth ore face challenges such as low leaching efficiency, environmental pollution, high reagent consumption, and complex processes, particularly in achieving high-grade rare earth concentrates while managing thorium and fluorine byproducts.
Innovation Solution
A mixed rare earth concentrate mineral and suspended mineral phase transformation-clean leaching system that employs low-temperature phasing transformation, fluidization processes, and controlled gas environments to prevent cerium oxidation and fluorine gas generation, utilizing a sequence of cyclone separators, fluidization sealing valves, and leaching tanks to enhance rare earth recovery and minimize waste.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If concentrated sulfuric acid roasting process is used, then processing requirements are reduced and operation flow is simplified, but environmental pollution increases and thorium pyrophosphate cannot be recycled
Solution Approach 1:
The patent changes the chemical parameters by using hydrochloric acid instead of concentrated sulfuric acid, and controls the temperature parameter at 800-900°C to prevent thorium pyrophosphate formation while maintaining processing efficiency
Solution Approach 2:
The patent converts the harmful effect of thorium oxidation into a beneficial process by controlling roasting conditions to form recyclable thorium compounds rather than difficult-to-handle pyrophosphates, enabling resource recovery
2Object-generated harmful factors
If alkali decomposition method is used, then production manner is cleaner and comprehensive resource recovery efficiency is higher, but reagent consumption increases and equipment corrosion worsens
Solution Approach 1:
The patent changes the chemical reagent from alkali to hydrochloric acid, and adjusts temperature parameters to 800-900°C, achieving cleaner production with reduced reagent consumption and less equipment corrosion
Solution Approach 2:
The patent uses hydrochloric acid as an alternative to alkali decomposition, copying the decomposition function while avoiding the drawbacks of alkali consumption and corrosion through different chemical mechanisms
3Productivity
If hydrochloric acid leaching process is used after oxidation roasting, then cerium and thorium can be recovered, but chlorine gas is generated and fluorine waste gas is produced
Solution Approach 1:
The patent performs preliminary action by pre-roasting the mineral to convert Ce4+ to Ce3+ and stabilize fluorine before leaching, preventing harmful gas generation during the subsequent hydrochloric acid treatment while maintaining recovery efficiency
Solution Approach 2:
The patent converts the potentially harmful Ce4+ oxidation state into beneficial Ce3+ through controlled roasting, and transforms fluorine from a waste gas problem into a stable compound that can be managed during leaching
4Ease of manufacture
If conventional ore dressing methods are used, then processing is simple, but high-grade rare earth concentrates cannot be obtained
Solution Approach 1:
The patent changes the fundamental processing parameters by using hydrochloric acid leaching at controlled temperatures instead of conventional gravity separation, achieving high-grade concentrates while maintaining operational simplicity through a streamlined process
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 system achieves higher leaching rates of rare earth minerals, reduces reagent costs, and eliminates fluorine and chlorine waste gas emissions, thereby improving environmental sustainability and operational efficiency.
Implementation Method 1
low-temperature phasing transformation of a rare earth mineral
Implementation Method 2
avoid generation of cerium tetravalent in mineral phase transformation products
Implementation Method 3
fluidization processes
Implementation Method 4
sequence of cyclone separators
Implementation Method 5
clean leaching system
Data Source
AI summary
A mixed rare earth concentrate mineral and suspended mineral phase transformation-clean leaching system and a method thereof achieve low-temperature phasing transformation of a rare earth mineral. The system includes a Venturi dryer, a multi-stage separator, a suspension preheating decomposition furnace, a multi-state fluidization sealing valve, a mineral phase transformation machine, a ball mill, a multi-stage acid leaching tank, an alkali leaching tank and a neutralization tank. The method includes: after preheating mixed rare earth concentrate mineral powder, placing the preheated mixed rare earth concentrate mineral powder in a suspension preheating decomposition furnace for preheating decomposition to enable the powder to be in the suspension state, after cyclone separation, introducing the powder to a mineral phase transformation machine for mineral phase transformation, after ball milling, performing acid washing, performing alkali decomposition on acid leached residues, performing acid leaching twice on acid liquor, and neutralizing leached products to obtain neutralization residues.