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Method for extracting gold from waste circuit boards

A waste circuit board and immersion gold technology, which is applied in the field of industrial waste recycling, can solve a large number of problems with high equipment requirements, and achieve the effects of avoiding environmental pollution, simple equipment, and strong practical significance

Inactive Publication Date: 2008-07-30
DONGHUA UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0007] The technical problem to be solved in the present invention is to provide a method for extracting gold from waste circuit boards, to solve the problem of the large amount of toxic nitrogen oxide gas produced by the conventional nitric acid-aqua regia process, the high requirements for equipment and the generation of gold in cyanide extraction technology. A series of other problems such as a large amount of cyanide-containing sewage, to achieve green, cheap and efficient extraction of gold from waste circuit boards

Method used

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Experimental program
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Effect test

Embodiment 1

[0038] Using waste circuit boards as raw materials, after pretreatment such as crushing and sorting, the metal particle components were analyzed by microwave digestion ICP-AES method. In view of the very high copper content, the national standard method (iodometric method) was used for analysis. The results are shown in Table 1.

[0039] Table 1 shows the content of main metal elements in waste circuit boards

[0040]

[0041]Pour the metal particles, nitric acid and sulfuric acid mixed acid solution (the concentration of nitric acid is 1.0 mol / L, the concentration of sulfuric acid is 2.5 mol / L) into the reactor, the solid-liquid ratio of the two is 1:10, stir and react at a constant temperature of 55 ° C for 1.5 h , the stirring speed is 500r / min, and a small amount of nitrogen oxide produced in the reaction is absorbed by water to obtain dilute nitric acid as a by-product. The reacted mixture is cooled and filtered, and the filtrate adopts conventional methods to recover...

Embodiment 2

[0043] Pour the metal particles, nitric acid and sulfuric acid mixed acid solution (the concentration of nitric acid is 1.0 mol / L, the concentration of sulfuric acid is 3 mol / L) into the reactor, the solid-liquid ratio of the two is 1:10, stir and react at a constant temperature of 60 ° C for 1.5 h, The stirring speed is 500r / min, and a small amount of nitrogen oxide produced in the reaction is absorbed by water to obtain dilute nitric acid as a by-product. The reacted mixture is cooled and filtered, and the filtrate adopts conventional methods to recover copper, and the filter residue and dilute nitric acid solution enter the reactor for secondary dissolution of base metals, the solid-liquid ratio is 1:10, the nitric acid concentration is 1.0mol / L, and the reaction is stirred at room temperature 0.5h, the stirring speed is 300r / min. Also use water to absorb a small amount of nitrogen oxides produced by the reaction, cool and filter the reacted mixture, wash and dry the residu...

Embodiment 3

[0045] Using waste circuit boards as raw materials, after pretreatment such as crushing and sorting, the metal particle components were analyzed by microwave digestion ICP-AES method. In view of the very high copper content, the national standard method (iodometric method) was used for analysis. The results are shown in Table 1. Pour the metal particles, nitric acid and sulfuric acid mixed acid solution (the concentration of nitric acid is 1.0 mol / L, the concentration of sulfuric acid is 2.5 mol / L) into the reactor, the solid-liquid ratio of the two is 1:10, stir and react at a constant temperature of 60°C for 2 hours, The stirring speed is 500r / min, and a small amount of nitrogen oxide produced in the reaction is absorbed by water to obtain dilute nitric acid as a by-product. The reacted mixture is cooled and filtered, and the filtrate adopts conventional methods to recover copper, and the filter residue and dilute nitric acid solution enter the reactor for secondary elution ...

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Abstract

The invention relates to a method by which gold can be extracted form waste circuit boards. Secondary acid dipping can be used for pre-processing metal particles of waste circuit boards. A first leaching uses mixed acid solution of nitric acid and sulphuric acid to leach out base metals which mainly is copper and can be used for wrapping gold in circuit boards. The diluted nitric acid solution can be used for dissolving out base metals secondarily to create favorite condition for the following gold extracting. A little nitrogen oxides can be absorbed by water, and then non-cyanogen complexing agent thiourea can be used for selectively leaching out gold and silver; finally, base-metal ferrous powder can be used for displacing gold and silver form the leaching solution, thereby realizing the source recycling of gold and silver. With simple equipment and convenient operation, the method has great potential in industrial promotion. The invention recycles copper and silver when gold is extracted form waste circuit boards, thereby having considerable economic, social and environmental benefits.

Description

technical field [0001] The invention belongs to the field of industrial waste recycling, and more particularly relates to a method for extracting gold from waste circuit boards. Background technique [0002] With the continuous high growth of electronic waste, its harmless treatment, disposal and resource reuse have become key issues that need to be solved urgently in economic development. [0003] As the core component of various electronic products, the circuit board contains about 40% metal, 30% plastic and 30% oxide from the analysis of its composition. The recycling of other components has obvious advantages. Its recycling technology mainly realizes the approximate separation of metals and non-metals through crushing, sorting and other pretreatment processes. The metal with the highest content is copper, and the metal with the highest recovery value is gold. The conventional recovery process is the nitric acid-aqua regia process. The method is to dissolve copper in ni...

Claims

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Application Information

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IPC IPC(8): C22B11/00C22B3/06
CPCY02P10/20
Inventor 陈亮吴骏邱丽娟陈东辉黄满红潘洲
Owner DONGHUA UNIV
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