Method of smelting and recycling tin in abandoned circuit board powder through multi-component mixed molten salt under alkaline environment

Abstract

The invention discloses a method of smelting and recycling tin in abandoned circuit board powder through multi-component mixed molten salt under the alkaline environment. The method includes the following steps: (1) low-temperature oxidizing smelting is conducted, namely, the abandoned circuit board powder and a multi-component alkaline medium are evenly mixed by the mass ratio of 1:(1-8) and are then heated to 100-300 DEG C, and oxygen is led to conduct smelting for 30-100 minutes to obtain smelting products; (2) water logging dissolving is conducted, namely, water is added in the smelting products to conduct leaching and filtering to obtain a leaching agent and leaching residues, wherein metal like tin, zinc and aluminum is contained in the leaching agent, and copper, lead and precious metal are contained in the leaching residues; (3) evaporative crystallization is conducted, namely, alkali is added into the obtained leaching agent to keep the total alkali mass concentration of the leaching agent at 350-550g / L, and then heating, evaporative crystallization, filtering and washing are conducted to obtain sodium stannate products. According to the method, due to the adoption of the multi-component mixed alkaline medium, the smelting temperature is greatly reduced, smelting conditions are optimized, and energy consumption and operation cost are further reduced.

Description

technical field [0001] The invention relates to a method for valuable metals in circuit board powder, in particular to a method for recycling tin in waste circuit board powder by alkaline smelting of multiple mixed molten salts. Background technique [0002] With the faster and faster replacement of electronic products, a large number of circuit boards are discarded. Circuit boards contain metals of great economic value such as tin and copper, which have great potential for recycling. At present, the recovery of tin in waste circuit boards at home and abroad mainly uses heating to remove tin. However, this method will cause pyrolysis of organic matter and produce a large amount of toxic and harmful gases, which has caused great harm to the environment and the health of operators. It is impossible to completely remove tin from the circuit board, resulting in a waste of resources. [0003] Chinese published patent CN1288795A (disclosure date 2001.3.28) proposes a solder reco...

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Problems solved by technology

However, this recycling method requires a large amount of metal particles and high-temperature media, resulting in waste and the metal particles cannot be recycled. In addition, this device can only process a single waste circuit board, the separation efficiency is very low, and it will also cause certain environmental pollution. Pollution

Chinese patent CN203533568U (public date 2014.04.09) proposes an integrated rotary kiln for detinning and incineration, which is divided into two parts, the front part is a detinning chamber, and the rear part is an incineration chamber. The position of the chamber is low, and the two sections are driven by the drive motor to rotate together, but this method can only remove part of the tin, and there is still a small amount of tin embedded in the circuit board that is difficult to remove

However, the cost of preparing liquid oil by this method is too high and it is difficult for industrial application

Chinese published patent CN101423898A (publication date 2009.05.06) proposes to heat the waste circuit boards in an oil bath to melt the solder, and then use a centrifugal machine to efficiently separate the solder from the waste printed circuit boards, Then separate organic matter and other metals by vacuum pyrolysis, but this method will decompose certain organic matter and produce polluting gas when pyrolyzing molten tin

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