Electrodialytic Preparation of Phosphoric Acid and Device

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This patent describes a method and device for producing phosphoric acid and calcium hydroxide using electrodialysis. The process uses a 5-chamber electrodialysis cell to separate a solution containing calcium phosphate salts and an aqueous solution containing inorganic salts under an electric field. Ion exchange membranes are used to divide components into a calcium salt concentrate, phosphoric acid, and a base. The system can handle impure inputs, operates continuously, and mitigates issues common in previous methods, such as membrane scaling due to insoluble hydroxide formation.

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• Industrial production of phosphoric acid from phosphate-containing waste or minerals
• Recovery of phosphoric acid from industrial wastewater or byproducts
• Manufacturing fertilizer-grade phosphoric acid and associated calcium compounds
• Simultaneous production of calcium hydroxide, which can be used for water treatment or other chemical processes
• Resource recovery in the circular economy (e.g., from municipal sludge or waste streams)
• Phosphate recycling in environmental remediation projects
• Production of pure calcium salts for chemical or food industry

BenefitsContent extracted from patent full text and abstract with AI.

• Efficiently produces concentrated phosphoric acid without extensive pre-purification of inputs
• Allows processing of impure or waste-derived calcium phosphate without severe membrane fouling
• Reduces operating and treatment costs by minimizing or eliminating pre-cleaning steps
• Enables continuous, scalable operation in an industrial context
• Simultaneously generates valuable byproducts (calcium hydroxide, sodium hydroxide, calcium chloride)
• Minimizes environmental waste by transforming low-value waste streams into marketable chemicals
• Improves membrane longevity by avoiding calcium hydroxide precipitation and scaling

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Patent Abstract

Die Erfindung betrifft ein Verfahren und eine Vorrichtung zur elektrodialytischen Herstellung von Phosphorsäure und Calciumhydroxid bei dem ein verunreinigtes wässriges Diluat, enthaltend mindestens ein gelöstes Calciumphosphatsalz, und eine wässrige Salzlösung, enthaltend mindestens ein anorganisches Salz durch eine 5-Kammer-Elektrodialysezelle geleitet werden, wobei Calciumphosphatsalz und anorganisches Salz mittels Transport ionischer Komponenten über Ionenaustauschmembranen unter Triebkraft eines elektrischen Feldes in ein calciumsalzhaltiges wässriges Konzentrat, eine wässrige Phosphorsäure und eine wässrige Base getrennt werden, wobei das Diluat, die Salzlösung, das Konzentrat, die Phosphorsäure und die Base in fünf Prozessströmen im kontinuierlichen Kreislauf geführt werden.