{"id":316,"date":"2026-07-08T15:36:52","date_gmt":"2026-07-08T07:36:52","guid":{"rendered":"https:\/\/www.rubri.cn\/indie_testimonial\/v2-case-6\/"},"modified":"2026-10-27T07:18:13","modified_gmt":"2026-10-26T23:18:13","slug":"mixed-acid-recovery-steel-60m3d","status":"publish","type":"indie_testimonial","link":"https:\/\/www.rubri.cn\/en\/indie_testimonial\/mixed-acid-recovery-steel-60m3d\/","title":{"rendered":"Diffusion dialysis (DD) used in a 60 m\u00b3\/day hydrofluoric acid and nitric acid recovery and treatment project for a steel company"},"content":{"rendered":"<p>Diffusion dialysis (DD) is used in a 60 m\u00b3\/day hydrofluoric acid and nitric acid recovery treatment project for a steel enterprise, showing the treatment scale and operating indicators of this technical route in similar projects.<\/p>\n<h2>Key indicators<\/h2>\n<ul>\n<li>Treatment capacity: 60 m\u00b3\/day<\/li>\n<li>Number of units: 10<\/li>\n<li>Membrane area: 500 m\u00b2<\/li>\n<li>Recovery rate: 80%<\/li>\n<li>Rejection rate: 93%<\/li>\n<\/ul>\n<h2>Project background<\/h2>\n<p>Stainless steel pickling generally uses a mixed acid system of hydrofluoric acid and nitric acid. During pickling, the acids are consumed while metal ions continue to accumulate, forming waste mixed acid.<\/p>\n<p>Hydrofluoric acid in the mixed acid is relatively expensive and is a controlled material; direct neutralization and discharge both wastes resources and increases disposal costs.<\/p>\n<p>The project aims to separate free acid from metal salts without changing the composition of the acid system, achieving mixed acid recovery and reduction.<\/p>\n<h2>Process route<\/h2>\n<ul>\n<li>A hydrofluoric acid-resistant diffusion dialysis anion-exchange membrane is used, relying on the concentration difference to drive preferential permeation of free acid.<\/li>\n<li>Hydrofluoric acid and nitric acid molecules and acid ions migrate to the water side to form regenerated mixed acid, while metal ions such as iron, chromium, and nickel are retained.<\/li>\n<li>The pretreatment section includes filtration and temperature adjustment to control influent suspended solids and maintain stable membrane flux.<\/li>\n<li>The recovered mixed acid is returned for use according to the pickling bath solution formulation requirements, and the residual liquid enters the subsequent neutralization treatment process.<\/li>\n<\/ul>\n<h2>Operating performance<\/h2>\n<ul>\n<li>Treatment capacity: 60 m\u00b3\/day.<\/li>\n<li>Membrane stack equipment: 10 units.<\/li>\n<li>Membrane area: 500 m\u00b2.<\/li>\n<li>Acid recovery rate: 80%.<\/li>\n<li>Impurity rejection rate: 93%.<\/li>\n<\/ul>\n<h2>Illustrative materials<\/h2>\n<div class=\"iw-media-grid\">\n<figure><img decoding=\"async\" width=\"650\" height=\"488\" src=\"\/wp-content\/uploads\/2026\/07\/v2-cfd9ef986a13.jpeg\" class=\"attachment-large size-large\" alt=\"\u6269\u6563\u6e17\u6790\u7528\u4e8e\u67d0\u94a2\u94c1\u4f01\u4e1a60\u65b9\/\u5929\u6c22\u6c1f\u9178\u3001\u785d\u9178\u56de\u6536\u5904\u7406\u9879\u76ee\" loading=\"lazy\" \/><figcaption>Illustration of diffusion dialysis (DD) used in a 60 m\u00b3\/day hydrofluoric acid and nitric acid recovery treatment project for a steel enterprise<\/figcaption><\/figure>\n<\/div>","protected":false},"featured_media":132,"menu_order":60,"template":"","meta":{"site-sidebar-layout":"default","site-content-layout":"","ast-site-content-layout":"default","site-content-style":"default","site-sidebar-style":"default","ast-global-header-display":"","ast-banner-title-visibility":"","ast-main-header-display":"","ast-hfb-above-header-display":"","ast-hfb-below-header-display":"","ast-hfb-mobile-header-display":"","site-post-title":"","ast-breadcrumbs-content":"","ast-featured-img":"","footer-sml-layout":"","ast-disable-related-posts":"","theme-transparent-header-meta":"","adv-header-id-meta":"","stick-header-meta":"","header-above-stick-meta":"","header-main-stick-meta":"","header-below-stick-meta":"","astra-migrate-meta-layouts":"default","ast-page-background-enabled":"default","ast-page-background-meta":{"desktop":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center 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