Non-ferrous smelting heavy metal wastewater recycling

Non-ferrous Smelting Wastewater Recycling

1. The quality of domestic non-ferrous metallurgy heavy metal wastewater has the following three major characteristics:

(1) High content of heavy metals and recyclable resources;

(2) Large water quantity, complex water quality and difficult to treat;

(3) High content of calcium and chlorine in the neutralized water when recyling directly

In a hydrometallurgical enterprise with an annual output of 100,000 tons of zinc smelting, the total wastewater discharge is 80x104m³/year; the total water consumption is 2800x104m³/year, the recycled water amount is 2700x104m³/year, of which the fresh water amount is 131x104m³/years. 

2. Basic content of each component in production wastewater is shown in the following table: (mg/L)

3. Principles of The treatment Process

Based on wastewater quality characteristics and reuse water quality requirements of the production system, acidic wastewater from wet workshop, wastewater from chemical water treatment station, rinsing surface water and wastewater undergoing contaminated acid treatment are directly discharged into the sewage regulating reservoir. Flocculating settling is employed, and the composite membranes carry out evaporation and crystallization of MVR. The treated effluent thus reaches the water quality standards for production reuse. The combination process is mature and reliable. It has reliable water quality and stability, which can not only recover valuable metals in waste water resources, but also achieve water recycling.

The water production indicators for the process are as follows:

4. The Project Implementation Effect

1)        Using the combination membrane to process smelting waste water and reach zero discharge;

2)        The overall process has high water quality that can be reused to supply medium to high pressure filtration to replace the water softening system;

3)        The process does not contain chemicals and is of low operating cost; the system operates stably, has a high degree of self-control, and strong expansion ability.

3. Analysis of Operating Cost

To day processing 2400 tons of wastewater (100000 tons/year zinc smelting scale) accounting

Annual water yield:792,000 m³

Direct operating cost: 6,336,000 yuan/year

Unit processing costs: 8-9yuan/m³（recycle-water cost）