Jiujiang Precious Metals Refinery: Emission Control Project Overview

Jiujiang Platinum-Palladium Precious Metals Refining Project

Project Overview

This project officially launched in April 2021. Our team designed it specifically to treat exhaust gases that the silver and platinum-palladium refining processes generate in the smelter’s first workshop. These gases include high-concentration nitrogen oxides from nitric acid silver dissolution, as well as alkaline exhaust that the platinum-palladium complexing tanks release.

Treatment Process

To handle the high-concentration nitrogen oxides that the silver nitric acid dissolution produces, the project employs a multi-stage approach:

• First, two-stage bubble absorption

• Then, three-stage jet absorption

• Next, two-stage Venturi treatment

• Finally, two-stage alkaline spray treatment

For the alkaline exhaust resulting from platinum-palladium complexing, the system uses:

• Initially, one-stage Venturi treatment

• Subsequently, one-stage acid spray treatment

After these steps, the system collects all acidic exhaust and directs it into a two-stage alkaline spray tower. Similarly, it gathers alkaline waste gas and processes it in a one-stage acid spray tower. Ultimately, the treated exhaust exits through a chimney.

The project must comply with strict emission standards:

• Nitrogen oxides below 100 mg/m³

• Additionally, ammonia below 5 mg/m³

Operational Performance

The project began operating in April 2021 and includes a comprehensive online monitoring system. Initially, the workshop emits nitrogen oxides at 30,000 mg/Nm³, ammonia at 4,000 mg/Nm³, and hydrochloric acid, nitric acid, and sulfur dioxide at 400 mg/Nm³.

However, actual emissions after treatment remain well below required limits:

• Nitrogen oxides reached only 40 mg/m³

• Similarly, ammonia measured just 1 mg/m³

• Furthermore, monitors detected no acidic gases such as HCl, HNO₃, or SO₂

As a result, the project continues to operate smoothly with no equipment failures.

Additional Contract & Outcome

Following the successful bid in September 2020, our company signed an agreement with the lead-zinc smelter to treat high-concentration nitrogen oxides from their silver nitric acid dissolution. Accordingly, we implemented:

• Two-stage bubble absorption

• Then, four-stage jet absorption

• Finally, one-stage alkaline spray

We launched this system in January 2021. Subsequent third-party tests confirmed that nitrogen oxide emissions measured only 40 mg/m³, significantly below the contract requirement of 100 mg/m³. Consequently, the client highly appreciated our performance.