Alkaline Earth Metal Bleaching Composition for Pulp Slurry Stability
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Solution Overview
Problem
Traditional pulp bleaching processes face inefficiencies due to the sparing solubility of alkaline earth metal hydroxides and oxides, leading to reduced bleaching efficiency and pulp viscosity, along with the need for expensive and hygroscopic magnesium sulfate as a radical scavenger and slurry stabilizer.
Innovation Solution
A composition comprising alkaline earth metal oxides or hydroxides, alkaline earth metal salts, and pitch control additives, such as talc and bentonite, which improves solubility and stability, reducing the formation of harmful deposits and maintaining pulp viscosity, while allowing for pH control and reduced use of expensive raw materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If alkaline earth metal hydroxides and oxides are used to replace sodium hydroxide, then cost is reduced and environmental impact is improved, but solubility is poor leading to reduced bleaching efficiency
Solution Approach 1:
The patent introduces water glass (sodium silicate) as an intermediary substance that enhances the solubility and dispersibility of alkaline earth metal hydroxides and oxides in the pulp slurry. The water glass acts as a mediator between the insoluble alkaline earth metals and the aqueous environment, allowing efficient bleaching without requiring high solubility of the alkaline earth metals themselves.
Solution Approach 2:
The patent changes the physical and chemical parameters of the alkaline earth metal compounds by controlling particle size, surface area, and chemical form. By using finely divided forms and controlling the basicity (through water glass addition), the patent optimizes the reactivity and effective solubility of these compounds while maintaining their cost and environmental advantages.
2Reliability
If magnesium sulfate is used as radical scavenger and slurry stabilizer, then pulp viscosity is maintained and slurry stability is improved, but cost increases and storage becomes difficult due to hygroscopic properties
Solution Approach 1:
The patent replaces expensive and difficult-to-store magnesium sulfate with readily available, non-hygroscopic alkaline earth metal compounds such as calcium carbonate, calcium oxide, or calcium hydroxide. These substitutes provide similar slurry stabilization functions without the storage and handling problems of hygroscopic materials, effectively using cheaper, easier-to-manage substances.
Solution Approach 2:
The patent changes the chemical composition from hygroscopic magnesium sulfate to non-hygroscopic calcium-based compounds. This parameter change in chemical composition eliminates the hygroscopic property while maintaining the functional benefits of radical scavenging and slurry stabilization, improving ease of manufacture and storage.
3Quantity of substance
If alkaline earth metal hydroxides and oxides are used, then cost is reduced compared to sodium hydroxide, but bleaching efficiency decreases due to low solubility
Solution Approach 1:
The patent uses water glass as a mediator to bridge the gap between low-cost, low-solubility alkaline earth metal hydroxides/oxides and the aqueous bleaching environment. The water glass enhances the effective solubility and reactivity of these inexpensive compounds, allowing cost reduction without sacrificing bleaching efficiency.
Solution Approach 2:
The patent creates a composite system combining alkaline earth metal hydroxides/oxides with water glass (sodium silicate). This composite approach allows the inexpensive alkaline earth metals to provide cost savings while the water glass component ensures adequate solubility and reactivity, achieving both economic and performance goals.
4Reliability
If traditional chelating agents like EDTA are used, then metal ion removal is improved and peroxide efficiency increases, but environmental impact and cost increase
Solution Approach 1:
The patent replaces expensive, environmentally problematic chelating agents like EDTA with simple, inexpensive, and environmentally benign alternatives such as water glass (sodium silicate) and alkaline earth metal compounds. These substitutes provide adequate metal ion management without the persistence and environmental toxicity of traditional chelators.
Solution Approach 2:
The patent converts potentially harmful metal ions that would normally require strong chelators into beneficial components by using water glass and alkaline earth metals to manage them in an environmentally friendly manner. The approach transforms a harmful factor (metal ions requiring strong chelators) into an opportunity to use simpler, greener chemistry.
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 composition enhances bleaching efficiency, maintains pulp viscosity, and reduces the formation of unwanted side products, making the process more cost-effective and environmentally friendly by stabilizing pulp strength and reducing the need for complex procedures.
Implementation Method 1
the alkalinity of the described chemical preparation was reduced, leading to improved solubility of the alkaline earth metal oxide and/or alkaline earth metal hydroxide in this preparation
Implementation Method 2
the beneficial radical scavenging and slurry stabilising effects of the alkaline earth metal salt
Implementation Method 3
pitch control additives... lead to a reduction in fatty acid salts and resins in paper pulps
Implementation Method 4
Bentonite may bind heavy metals in the paper bleaching composition and reduce their interference with the bleaching process
Data Source
AI summary
The present invention relates to compositions for use in an aqueous pulp bleaching process, comprising one or more alkaline earth metal oxides and/or one or more alkaline earth metal hydroxides; one or more alkaline earth metal salts; and optionally, one or more pitch control additives. Methods and kits for the formation of said compositions, are also part of the invention, as is the use of said compositions, methods and kits.