Erdite Rod Particles from Iron Mud for Water Treatment
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Solution Overview
Problem
Current methods for preparing Erdite crystals using iron-containing waste mud in underground water plants are time-consuming, costly, and limited to laboratory-scale production, with low crystallinity and limited applicability in industrial settings.
Innovation Solution
A method involving mechanical dehydration of aqueous iron mud, addition of sodium sulfide, heating, and centrifugal treatment to produce Erdite rod-shaped particles (NaFeS2.2H2O) without the need for drying or removal of impurities, allowing for recycling of supernatant and reduced sodium sulfide usage, facilitating large-scale industrial production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If chemically pure iron carbonate is used as raw material to prepare Erdite crystals, then the crystallinity of the product is improved, but the preparation time increases and the process becomes complex
Solution Approach 1:
The patent changes the raw material parameter from chemically pure iron carbonate to iron-containing waste mud with specific composition ranges (Fe2O3: 30-70%, MnO2: 5-20%, SiO2: 5-20%). This parameter change enables direct preparation of high-purity Erdite crystals without time-consuming purification steps, achieving both high crystallinity and short preparation time simultaneously
Solution Approach 2:
The patent utilizes iron-containing waste mud as a low-cost, readily available raw material instead of expensive chemically pure iron carbonate. The waste mud is processed directly into high-value Erdite crystals, transforming a disposable waste product into a valuable resource while significantly reducing preparation time and cost
2Manufacturing precision
If H2S gas is introduced to water solution mixed by iron oxide colloid and NaOH for several days, then Erdite crystals are prepared, but the process requires heating conditions and multiple steps
Solution Approach 1:
The patent merges multiple process steps into a single reaction process. Instead of separately adding H2S gas, iron oxide colloid, and NaOH solution in multiple steps, the invention combines iron-containing waste mud (which contains Fe2O3, MnO2, SiO2 in specific ratios) with Na2S solution in one step to directly form high-purity Erdite crystals, eliminating the need for heating conditions and multiple processing steps
Solution Approach 2:
The iron-containing waste mud serves multiple functions simultaneously: it provides the iron source, contains manganese that catalyzes the reaction, and its specific composition ensures direct crystal formation without requiring external additives or heating. The waste mud essentially performs the role of multiple reagents and process conditions in one material
3Ease of manufacture
If NaFeS2 is prepared from chemically pure Fe2O3 and Na2S2O3 powder, then the reaction is simplified, but the crystal structure is different from Erdite and requires additional treatment
Solution Approach 1:
The patent changes the raw material parameters to iron-containing waste mud with specific composition (Fe2O3: 30-70%, MnO2: 5-20%, SiO2: 5-20%) and uses Na2S solution instead of Na2S2O3 powder. This parameter change enables the reaction to proceed directly to high-purity Erdite crystals with the correct crystal structure, eliminating the need for additional treatment steps to convert NaFeS2 to Erdite
4Ease of manufacture
If aqueous iron mud is used directly without dehydration, then the preparation cost is reduced, but the moisture content affects the reaction efficiency
Solution Approach 1:
The patent optimizes the moisture content parameter of iron-containing waste mud to 60-80% through controlled dehydration. This parameter optimization maintains the cost advantage of using waste mud while improving reaction efficiency, as the optimal moisture range allows for effective reaction between iron compounds and sodium sulfide without excessive water interfering with the 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 method significantly lowers production costs, enhances crystallinity, and expands the application range of Erdite particles for water treatment, achieving efficient removal of organic matter and antibiotics, with improved adsorption capabilities and treatment efficiency compared to prior methods.
Implementation Method 1
adding sodium sulfide to the first aqueous iron mud to obtain a first mixture, wherein the ratio of the weight of the first aqueous iron mud to the volume of sodium sulfide is between 3% and 15%
Implementation Method 2
heating the obtained solution in an airtight manner to 140° C.-270° C., and keeping a constant temperature for 0.5 hr to 4 hr
Implementation Method 3
performing centrifugal treatment on the solution in step C to obtain a supernatant and a solid
Implementation Method 4
performing vacuum drying on the solid at 40° C.-60° C. for 24 hr to obtain Erdite rod-shaped particles
Data Source
AI summary
The present invention discloses a method for preparing Erdite rod-shaped particles for water treatment by utilizing iron-containing waste mud in an underground water plant. In the method, aqueous iron mud is subjected to mechanical dehydration to obtain a first aqueous iron mud; sodium sulfide is added to the first aqueous iron mud to obtain a first mixture, wherein the ratio of the weight of the first aqueous iron mud to the volume of sodium sulfide is between 3% and 15%; water of an equal volume is added to the first mixture, and the obtained solution is heated in an airtight manner to 140° C.-270° C.; centrifugal treatment is performed to obtain a supernatant and a solid, and the solid is subjected to vacuum drying at 40° C.-60° C. for 24 h to obtain Erdite rod-shaped particles. In the method, aqueous iron mud formed after precipitation of backwash wastewater is directly used, no drying treatment is needed, and silicon and aluminum and other impurities do not need to be removed, thereby saving costs; Na2S is directly added to iron mud which is subjected to mechanical dehydration, and adjustment of pH value is not needed, therefore, the preparation method is convenient; and a supernatant can be recycled, thereby lowering preparation cost, and expanding an application range of the method.