Partly Prehydrated Lime for Sludge Separation
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Solution Overview
Problem
Existing methods for solid-liquid separation, particularly in sludge treatment, face challenges with quicklime reacting violently with water, leading to heterogeneous mixtures and increased complexity, which hinders effective concentration, decontamination, and drying of solids.
Innovation Solution
The use of delayed reactivity partly prehydrated quicklime (DRQL), composed of CaO and Ca(OH)2, which delays the reaction with water, allowing for homogeneous mixing and sequential flocculation and desiccation in both pre-liming and post-liming operations without additional handling steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If quicklime (CaO) is added to sludge for solid-liquid separation, then the drying and decontamination effect is improved, but the reaction with water is violent and heterogeneous mixtures are formed
Solution Approach 1:
The patent applies preliminary action by pre-hydrating part of the quicklime to form a slaked lime component before use. This pre-prepared lime contains both CaO and Ca(OH)2, where the Ca(OH)2 acts as a buffer to moderate the violent reaction that would otherwise occur when pure quicklime contacts sludge water. The pre-hydration step prepares the reagent in advance to achieve both drying effectiveness and mixture homogeneity.
Solution Approach 2:
The invention uses a composite lime material consisting of both quicklime (CaO) and slaked lime (Ca(OH)2) components. This composite structure allows the material to provide the strong drying effect of quicklime while the slaked lime component moderates the reaction and promotes homogeneous mixing. The dual-component composition resolves the contradiction between effective water removal and mixture uniformity.
2Stability of the object's composition
If hydrated lime Ca(OH)2 is used for pre-liming, then homogeneous mixing is achieved, but the particle size is too small to increase porosity and promote desiccation
Solution Approach 1:
The patent employs a composite lime material that combines fine particles (for homogeneity) with coarser particles (for porosity enhancement). The composite contains both CaO and Ca(OH)2 in various particle sizes, where the distribution of particle sizes allows fine particles to ensure homogeneous mixing while coarser particles create pore structures that facilitate water removal and improve desiccation performance.
Solution Approach 2:
The invention applies local quality by having different particle sizes within the lime material serve different functions. Fine particles are distributed throughout the mixture to ensure homogeneity, while coarser particles are positioned to create channels and pores for water drainage. This spatial differentiation of particle functions resolves the contradiction between mixing quality and drying efficiency.
3Reliability
If additional handling steps are added to control lime reaction, then reaction control is improved, but process complexity increases
Solution Approach 1:
The patent eliminates the need for additional handling steps by incorporating the reaction control function into the lime material itself through pre-hydration. The dual-component lime (containing both CaO and Ca(OH)2) self-regulates the reaction rate and heat generation during sludge treatment, removing the need for separate cooling or pH adjustment steps that would increase process complexity.
Solution Approach 2:
The composite lime material is self-regulating in its reaction with sludge water. The Ca(OH)2 component automatically buffers the pH and moderates the exothermic reaction of CaO hydration, allowing the material to control its own reaction characteristics without external intervention. This self-service property simplifies the overall process by eliminating the need for additional control mechanisms.
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 approach enables efficient concentration, decontamination, and drying of solids with reduced risk of violent reactions, improving the homogeneity and dryness of separation cakes while simplifying the process and reducing costs.
Implementation Method 1
delayed reactivity quicklime (abbreviated to: "DRQL"), which contains CaO that reacts with H2O after a certain lag phase
Implementation Method 2
CaO that reacts with H2O after a certain lag phase
Implementation Method 3
the hydrated lime of the DRQL being used for the flocculation or concentration of the solid matter before separation
Implementation Method 4
the quicklime of said DRQL being used for the desiccation of said solid matter during or (better still) after separation
Implementation Method 5
the quicklime of said DRQL being used for the desiccation of said solid matter
Data Source
AI summary
A novel use of delayed reactivity partly prehydrated lime (“DRQL”), which is comprised of 40 to 98% by weight of CaO and of 60 to 2% by weight of Ca(OH)2, preferably of 80 to 92% by weight of CaO and of 20 to 8% by weight of Ca(OH)2, and more preferably of 85 to 90% by weight of CaO and of 15 to 10% by weight of Ca(OH)2, in the field of the separation of solid matter from the liquid of a suspension. The invention also involves a novel method for treating a sludge, in which the solid matter is concentrated, dried and recovered using the delayed reactivity partly prehydrated lime. It additionally relates to, as a novel industrial product, the purified sludge obtained according to the method.