Silica Composition Stabilizes Hydrogen Peroxide in Pulp Bleaching
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Solution Overview
Problem
The pulp and paper industry faces challenges in achieving high brightness of wood fibers without the disadvantages of conventional bleaching processes, such as loss of oxidizing agents, fiber loss, high organic load in effluents, low biodegradability of additives, silicate scaling, and high costs, while also seeking to reduce water consumption and effluent load.
Innovation Solution
A composition of a silica compound and an alkaline earth metal oxide or hydroxide, such as magnesium hydroxide, is pre-formulated and allowed to stand before use in bleaching processes, which improves bleaching efficiency, reduces fiber loss, and minimizes scaling and effluent issues, allowing for increased recycling of process water and cost optimization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional bleaching processes are used to achieve high brightness, then brightness is improved, but loss of oxidizing agents occurs
Solution Approach 1:
The patent applies preliminary action by pre-formulating the silica compound and alkaline earth metal oxide/hydroxide into a stable composition before the bleaching process. This pre-prepared composition ensures optimal conditions are established beforehand, reducing peroxide degradation during the actual bleaching operation and maintaining higher residual oxidizing agent levels.
2Illumination intensity
If conventional bleaching processes are used to achieve high brightness, then brightness is improved, but fiber loss occurs
Solution Approach 1:
The patent changes key process parameters by using an alkaline earth metal oxide or hydroxide (such as magnesium oxide or hydroxide) instead of conventional strong alkalis, and by employing a specific silica compound formulation. These parameter changes create a more controlled pH environment that achieves high brightness while minimizing fiber damage and loss.
3Illumination intensity
If conventional bleaching processes are used, then brightness is improved, but scaling occurs
Solution Approach 1:
The patent employs a silica compound formulation that prevents scaling without requiring long-term maintenance or special handling. The silica compound acts as a scale inhibitor during the bleaching process, allowing conventional equipment to be used without special anti-scaling measures, thereby eliminating the harmful scaling effect.
4Illumination intensity
If conventional bleaching processes are used, then brightness is improved, but effluent load increases
Solution Approach 1:
The patent changes the chemical parameters of the bleaching process by using hydrogen peroxide as the oxidizing agent in combination with silica compound and alkaline earth metal oxide/hydroxide. This parameter change results in a more environmentally friendly effluent profile with lower organic load and better biodegradability compared to conventional chlorine-based or strong alkali processes.
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 enhances bleaching efficiency, maintains ISO brightness, increases residual hydrogen peroxide, reduces fiber loss, and decreases scaling and effluent load, facilitating more efficient and cost-effective pulp treatment with improved water recycling.
Implementation Method 1
it is believed to participate in the chelation of heavy metals and to contribute to establishing the alkaline conditions required for a good bleach result
Implementation Method 2
Hydrogen peroxide based bleaching is conventionally performed at an alkaline pH in the presence of a silicate, such as sodium silicate commonly referred to as water glass
Implementation Method 3
hydrogen peroxide...does not contain chlorine. Hydrogen peroxide based bleaching is conventionally performed at an alkaline pH
Data Source
AI summary
The invention relates to a composition comprising a mixture of a silica compound and an alkaline earth metal oxide or alkaline earth metal hydroxide in an aqueous solvent, characterised in that the silica compound and the alkaline earth metal oxide or alkaline earth metal hydroxide together form the major part of the non-solvent matter of the composition. The invention also relates to a method for producing said composition comprising adding an alkaline earth metal oxide or alkaline earth metal hydroxide and a silica compound to an aqueous medium to form an aqueous mixture, and allowing said aqueous mixture to stand. The invention also relates to a method for treating cellulosic fibres using said composition.