Recycling of precious metals in e-waste

The resourceful treatment of e-waste has become the focus of attention in recent years, and the proper disposal of e-waste has become an important part of global environmental protection.

E-waste usually refers to electrical appliances, computers, mobile phones and various accessories such as CD-ROMs and batteries that have completely or partially lost their functions, or residual products and trimmings from the production process. Since e-waste and other renewable resources are rich in substances such as electronic waste, and their natural resources are very limited, the development of the recycling industry is more related to the rise and fall of many fields such as metallurgy, chemicals, machinery and information.

Recycling of metals in e-waste

The process of recovering metals from e-waste is complex and usually involves separating the metals from the impurities through high temperatures and then refining the various metals through several corresponding processes. Precious metals such as copper, gold, silver, platinum and palladium in e-waste are generally recovered through a converter process. the SUNY GROUP process for the recovery of e-waste containing precious metals is

1) Melting

After sampling the different e-wastes are homogeneously mixed and added to the melting furnace as raw material. Some fuel is added at the beginning of the incineration. When the furnace temperature is 1200°C to 1250°C and the energy contained in the PCBs is 35-36 GJ/t, the process is maintained by the energy released from the organic matter contained in the PCBs. The burning of plastics and the oxidation of aluminium metal during the smelting process gives off heat. To control the smelting temperature from becoming too high, silicates are added and the amount of plastic added is also controlled. During the smelting process, the molten e-waste has a slag layer at the top and copper at the bottom. The copper and a small amount of slag flow into the converter and the remaining slag is flocculated with the ore to recover some precious metals. The final remaining slag is stacked in the residue, which can be further concentrated and refined to recover the precious metals.

2) Refining

Copper from the smelter is added to the converter for mixed refining, where it is purified by blowing oxygen to melt the iron and sulphur in the copper and adding silicates to form the slag, which is at a temperature of around l200°C. The refining process in the converter is exothermic and the oxidation process provides enough heat to run the converter. The upper slag layer consists mainly of iron and zinc; the lower layer is blistered copper or white copper. The slag can be further purified to obtain the by-products iron sand and zinc slag, which are then processed by an electric furnace to obtain iron and zinc. The industrial waste gas produced in the converter is treated to obtain metal dust, which can be re-cycled.

3) Electrolysis

The blister copper (98% copper) obtained from the converter is cast into anode copper, the so-called anode casting, and the formed anode copper contains 99% copper and 0.5% precious metals. The copper electrodes are purified by electrolysis, using sulphuric acid and sulphate of copper as the electrolyte, with a DC current of approximately 20,000 amperes during the process. On the cathode plate 99.99% pure copper is generally obtained, while the precious metals and impurities remain on the anode plate as attachments to the anode and can be further refined. The precious metals are refined in refineries where gold, silver, platinum and palladium can be recycled.

Because of the high value of precious metal recovery in e-waste, we need a complete set of perfect technical equipment to carry out the recovery and reuse of precious metals.SUNY GROUP is a professional solid waste recycling equipment manufacturer, especially in e-waste recycling has rich experience and technology, if you are interested, or want to know more, you can contact us at any time to consult.