Salt-Containing Dust Treatment with Multi-Stage Brine Purification
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Solution Overview
Problem
Existing methods for treating salt-containing dusts from industrial plants are inefficient in recovering valuable materials and often result in costly disposal due to high salt and heavy metal content, which complicates their utilization.
Innovation Solution
A multi-stage process involving the use of an aqueous phase to dissolve salts, followed by heavy metal removal and fractional crystallization to separate alkali metal chlorides, utilizing a multi-stage arrangement with centrifuges and electrocoagulation for efficient salt recovery and purification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If conventional water washing methods are used to treat salt-containing dusts, then salt recovery is achieved, but heavy metal contamination and low purification efficiency worsen the usability of recovered materials
Solution Approach 1:
The treatment process is divided into multiple sequential stages: initial water washing to dissolve salts, followed by separate treatment steps for heavy metal removal (precipitation or adsorption), and final purification. This segmentation allows each harmful substance to be addressed by specialized treatment methods, effectively separating salt recovery from heavy metal removal operations.
Solution Approach 2:
Chemical reagents are introduced as intermediaries to facilitate selective removal of heavy metals. Precipitating agents (such as sulfides or hydroxides) or adsorbents are added to bind heavy metals, allowing them to be separated from the salt solution. This intermediary approach enables differential treatment of mixed contaminants.
2Manufacturing precision
If multi-stage purification processes are implemented to remove heavy metals, then material purity improves, but process complexity and operational costs increase
Solution Approach 1:
Heavy metal removal is performed as a preliminary step before final salt crystallization and recovery. By removing heavy metals early in the process, subsequent purification steps become simpler and more effective, as the bulk of contamination is eliminated beforehand. This preliminary action prevents heavy metals from interfering with later crystallization processes.
Solution Approach 2:
The process utilizes changes in physical and chemical parameters (pH adjustment, temperature control, oxidation-reduction potential) to selectively precipitate or adsorb heavy metals at different stages. By manipulating these parameters, the process achieves high purification efficiency without requiring equally complex mechanical separation systems.
3Productivity
If large quantities of water are used for washing and dissolution, then salt extraction efficiency improves, but water consumption and disposal costs worsen environmental impact
Solution Approach 1:
The process maintains continuous circulation and reuse of wash water through multiple treatment stages. Water that has dissolved salts is continuously processed through heavy metal removal, evaporation, and crystallization, with the purified water being reused for subsequent washing operations. This continuous cycle maximizes the useful action of each unit of water.
Solution Approach 2:
The process exploits phase transitions (evaporation and crystallization) to concentrate and recover salts from water. By controlling evaporation rates and crystallization conditions, salts are recovered in solid form while water is condensed and reused, effectively decoupling salt extraction efficiency from water consumption.
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 process effectively reduces heavy metal content and enhances the purity of recovered salts, enabling their reuse in various applications while minimizing water consumption and operational costs.
Implementation Method 1
contacting the saline dusts with an aqueous phase to form an aqueous solution by dissolving water-soluble components of the saline dusts in the aqueous phase
Implementation Method 2
precipitating some of the heavy metals and, optionally, calcium present in the brine and separating the precipitate from the brine
Implementation Method 3
subjecting the brine to electrocoagulation, separating a flocculation product containing the heavy metals remaining in the brine
Implementation Method 4
subjecting the brine to fractional crystallization
Data Source
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AI summary
The present invention relates to a method for treating salt-containing dusts which accumulate during operation of industrial plants, e.g. in waste incineration plants, or during operation of rotary kilns, e.g. in cement production plants or clinker production plants. The method comprises: a step a) of forming an aqueous solution by bringing salt-containing dusts into contact with an aqueous phase; a step b) of removing heavy metals from the aqueous solution; and a step c) of separating alkali metal chlorides from the aqueous solution; and salt-containing dusts are brought into contact with an aqueous solution in step a) by means of a multi-stage arrangement through which the salt-containing dusts and the aqueous phase pass in opposite directions.