Case Study: High-Efficiency Nitrogen Oxide (NOx) Exhaust Gas Treatment in Precious Metal Refining

Project Background & Overview

In the precious metal refining and hydrometallurgy industries, treating hazardous emissions is as critical as recovering the metals themselves. Zhengzhou Jinquan Precious Metal Refining Equipment Co., Ltd. recently engineered, manufactured, and commissioned a comprehensive Nitrogen Oxide (NOx) Exhaust Gas Treatment EPC Project for a major smelting facility.

During the wet chemical refining of gold, silver, and platinum group metals (PGMs), the dissolution of raw materials using nitric acid generates massive volumes of high-concentration, highly toxic nitrogen oxides ($\text{NO}_x$, primarily $\text{NO}$ and $\text{NO}_2$). Left untreated, these gases pose severe environmental hazards and violate stringent industrial emissions standards.

The Technical Challenge

The exhaust stream generated during hydrometallurgical refining presents unique challenges that standard air scrubbers cannot handle:

• Extreme Concentration Spikes: Sudden bursts of high-concentration $\text{NO}_x$ during acid-leaching reactions.

• Low Component Reactivity: Nitric oxide ($\text{NO}$) is highly insoluble in water, making traditional caustic scrubbing ineffective on its own.

• Corrosive Environment: The presence of acidic mists demands highly durable, corrosion-resistant equipment materials.

Zhengzhou Jinquan’s Tailored NOx Solution

https://www.goldsrefining.com/product_cat/nitrogen-oxide-treatment-equipment/

As a leading provider of integrated precious metal refining and flue gas treatment solutions, Zhengzhou Jinquan implemented a multi-stage, closed-loop NOx Exhaust Gas Treatment System.

1. Advanced Oxidation Process (AOP)

Because $\text{NO}$ is difficult to absorb directly, the system introduces a specialized oxidizing agent in the initial stage. This converts insoluble $\text{NO}$ into highly soluble $\text{NO}_2$ according to the following chemical dynamic:

2. Multi-Stage Chemical Scrubbing Towers

The oxidized gas passes through a series of non-standard, high-efficiency vertical packed scrubbing towers. Utilizing a proprietary absorption liquid (combining reducing agents and alkaline solutions), the $\text{NO}_2$ is efficiently reduced to harmless nitrogen gas ($\text{N}_2$) and soluble salts:

3. Smart Automation & Corrosion Resistance

The entire system is constructed using premium, acid-resistant polymers (PPH/PVDF) to withstand long-term corrosive exposure. Additionally, it is integrated with an automated PLC control system that adjusts chemical dosing in real-time based on continuous emission monitoring data (CEMS).

Project Outcomes & Performance Data

The project successfully passed strict environmental compliance audits. The core performance metrics achieved include:

Why Choose Zhengzhou Jinquan for Waste Gas Treatment?

Zhengzhou Jinquan Precious Metal Refining Equipment Co., Ltd. provides turnkey EPC (Engineering, Procurement, and Construction) solutions for gold/silver electrolysis, PGM purification, and environmental engineering.

By combining cutting-edge precious metal extraction technologies with robust secondary pollution controls, Jinquan ensures that your refinery remains profitable, compliant, and sustainable.

Contact our technical engineering team today to customize a professional nitrogen oxide or acid mist treatment solution for your plant.

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