Sulfuric Acid Concentration
Vacuum Concentration and Purification Unit (VCU)
P&P Industries AG' Vacuum Concentration Unit (VCU) is specifically designed for the re-concentration of spent sulfuric acid (H₂SO₄) in applications where acid recovery and purification will improve the revenue of the production process. This is often used per example in the mining and metallurgical sectors.
The VCU process involves evaporating large volumes of water from weak sulfuric acid to recover it as a reusable, concentrated acid. During this process, dissolved metals and other contaminants are purified and neutralized from the acidic condensate, ensuring safe and efficient recovery.
Key Process Features:
- Multi-Stage Concentration:
The system uses multiple stages with varying pressures and boiling points to minimize energy consumption and maximize efficiency.
- Effective Purification:
Common impurities such as Cl, F, Hg, Se, Zn, Cu, As, Sb, Cd, V, Co, Ni, and P are removed or neutralized. Metal oxides are converted into sulfates during the process.
- Neutralization System:
Acidic vapors and condensates from each concentration stage are collected and treated in a neutralization unit. Neutralization agents like limestone are used to bind sulfur-containing compounds, halogens (e.g., Cl, F), and other contaminants. Depending on solubility, some compounds precipitate and are removed as a slurry.
- Flexible Configuration:
- Stage 1 (Pressurized): Concentrates spent acid from ~15% to ~25% by weight.
- Stage 2 (Vacuum): Further concentration to ~65–70% by weight.
- Optional Stage 3: Can increase concentration to ~90% by weight.
- While up to ~98% concentration is technically feasible, it is not considered economically viable for most applications.
Benefits:
- High recovery rates of reusable sulfuric acid
- Reduced environmental impact through safe handling of acidic waste
- Energy-efficient operation with minimal steam consumption
- Customizable system design for varying acid concentrations and impurity levels