Application Background

China’s total titanium dioxide production capacity reaches 3.5 million tons, and the sulfate process dominates domestic TiO₂ manufacturing. Large volumes of waste acid and wastewater are generated during sulfate-process production. Neutralization treatment will produce massive waste gypsum and trigger severe environmental pollution.

Statistics show that around 6 tons of dilute sulfuric acid with a concentration of 20%~25% is discharged per ton of titanium dioxide product. Evaporation technology is adopted to concentrate the dilute acid to 65% or higher, and the concentrated sulfuric acid can be recycled to upstream production sections.

Treatment Solutions

We provide two sets of treatment processes for selection:

Solution 1: Low-temperature Evaporation & Concentration Only to Raise Acid Concentration

This process adopts two-effect countercurrent forced circulation combined with flash evaporation. Full reuse of secondary steam drastically cuts steam consumption, making it specially suitable for titanium dioxide waste acid treatment.

Fully graphite-lined flash separation tanks are selected, with a service life of over 10 years.

Graphite evaporators are optimized structurally to boost heat transfer efficiency and reduce pressure drop.

两效蒸发工艺流程

Solution 2: Membrane Pre-treatment Unit

The membrane device separates TiO₂ solid particles and sulfate salts from dilute sulfuric acid. The purified dilute acid then flows into the evaporation system for concentration, effectively solving the frequent blockage issue of evaporators.

1. Microfiltration recovers TiO₂ solid particles contained in waste acid;
2. Ferrous sulfate is separated via freezing crystallization;
3. Nanofiltration (NF) concentrates and removes ferrous ions (Fe²⁺) from waste acid.

Sulfuric Acid Concentration Unit for Ningbo Xingfu Titanium Dioxide Plant