Direct Process Solids Passivation via Buffered Aqueous Neutralization
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Solution Overview
Problem
The commercial production of methylchlorosilanes and halosilanes through the direct process generates hazardous direct process solids that are prone to self-heating and oxidation, posing a fire hazard and requiring costly and wasteful passivation methods, such as quenching with alkaline substances or mixing with clay, which are inefficient and generate significant waste.
Innovation Solution
A method involving a mixture of clay, water, and a base is used to passivate direct process solids, reducing waste, equipment maintenance, and labor costs, while improving the properties of the resulting material by reducing dustiness and environmental and health risks, and shortening quenching times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If direct process solids are quenched by reaction with alkaline substance, then reactivity is neutralized, but reaction time is long and energy consumption increases
Solution Approach 1:
The invention changes the chemical parameters of the quenching system by using a buffered aqueous solution with specific pH (6-8) and controlled base concentration (0.1-5 M), replacing traditional strong alkaline substances. This parameter optimization enables rapid reactivity neutralization within 1-10 minutes while avoiding excessive energy consumption and unwanted side reactions.
2Object-affected harmful factors
If direct process solids are mixed with clay, then passivation is achieved, but waste generation increases and activity persists
Solution Approach 1:
The invention extracts and removes the harmful reactive species from direct process solids through chemical neutralization with buffered aqueous solution, separating the hazardous component (reactive silicon species) from the solid material. This extraction approach eliminates the need for clay mixing, reducing waste generation while achieving complete passivation.
Solution Approach 2:
The buffered aqueous solution acts as an intermediary medium that facilitates the neutralization reaction between reactive silicon species and base components. The buffer system (using substances like phosphates, carbonates, or borates) mediates the reaction to maintain controlled pH, ensuring complete passivation without excessive waste production.
3Reliability
If aqueous lime solution is used for quenching, then reactivity is reduced, but separation steps and equipment maintenance increase
Solution Approach 1:
The buffered aqueous solution serves multiple functions simultaneously: it neutralizes reactive species, controls pH to prevent unwanted reactions, facilitates easy separation of solids from liquids, and minimizes equipment fouling. This multi-functional approach simplifies the overall process compared to traditional lime solution methods that require separate handling for each function.
4Object-affected harmful factors
If large amount of water is added during quenching, then reactivity is controlled, but processing complexity and cost increase
Solution Approach 1:
The invention applies partial action by using a controlled, moderate amount of aqueous buffered solution rather than excessive water. The buffer concentration and volume are optimized to achieve sufficient reactivity control without creating overly dilute systems that would complicate subsequent processing and increase costs.
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 effectively neutralizes the reactivity of direct process solids, reduces inert material content, and enhances the consistency and handling of the passivated product, leading to increased copper recovery and reduced environmental impact.
Implementation Method 1
combining direct process solids with a passivating composition comprising clay, base, and water
Implementation Method 2
When in contact with moisture, such as atmospheric moisture, it evolves hydrogen gas, and it is highly susceptible to atmospheric oxidation and self-heating
Implementation Method 3
The new method reduces the passivated product's dustiness by improving its ability to be rewet
Data Source
AI summary
The invention pertains to a method of passivating direct process solids and to passivated and quenched compositions resulting from said method. The method of passivating direct process solids according to the invention comprises combining direct process solids with a passivating composition comprising clay, base, and water. The passivated composition of the invention comprises direct process solids and a passivating composition comprising clay, base, and water. The quenched composition of the invention comprises the passivated composition, wherein the passivated composition has been held for a sufficient period of time for the reactive species from the direct process solids to be substantially quenched and/or oxidized.