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Method for recovering silver from waste silver catalyst

A silver catalyst and slagging agent technology, applied in the field of silver recovery, can solve the problems of large environmental pollution, high silver content, and reduced silver recovery rate

Active Publication Date: 2013-09-04
GUIYAN RESOURCE YIMEN
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

The main disadvantages are: (1) A large amount of NO is produced when nitric acid dissolves silver x Exhaust gas and waste water cause great environmental pollution; (2) During the silver extraction process, the water quality, reagents, and halogens in spent catalysts have a greater impact on the silver recovery rate, and the high silver content in the insoluble residue reduces the silver recovery rate

Method used

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  • Method for recovering silver from waste silver catalyst

Examples

Experimental program
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Effect test

Embodiment 1

[0024] The waste silver catalyst used in the oxidation of ethylene to ethylene oxide, supported by α-Al 2 o 3 , the silver content is 16.84%, and the alumina content is 83.16%. First grind the waste silver catalyst to 100 mesh, take 500 grams of the ground waste silver catalyst, add 420 grams of lime (CaO), mix well, put it into a graphite crucible, heat it in a silicon-molybdenum rod high-temperature box-type electric furnace, and raise the temperature To 1500 ℃, heat preservation for 5 hours, cooling to normal temperature, the slag phase and the metallic silver phase are separated to obtain 83.27 grams of silver, the recovery rate of silver is 98.9%, and the silver purity is greater than 99.8%.

Embodiment 2

[0026] Take 500 grams of the waste silver catalyst that has been ground in Example 1, add 420 grams of lime (CaO), mix well, put it into a graphite crucible, heat it in a silicon-molybdenum rod high-temperature box-type electric furnace, raise the temperature to 1550 ° C, and keep it warm for 5 Hour, be cooled to normal temperature, slag phase and metal silver phase separation, obtain 83.52 grams of silver, the rate of recovery of silver is 99.19%, and silver purity is greater than 99.8%.

Embodiment 3

[0028] Take 500 grams of the waste silver catalyst that has been ground in Example 1, add 420 grams of lime (CaO), mix well, put it into a graphite crucible, heat it in a silicon-molybdenum rod high-temperature box-type electric furnace, raise the temperature to 1600 ° C, and keep it warm for 5 Hour, be cooled to normal temperature, slag phase and metal silver phase separation, obtain 83.73 grams of silver, the rate of recovery of silver is 99.44%, and silver purity is greater than 99.8%.

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Abstract

The invention discloses a method for recovering silver from a waste silver catalyst. The method is technically characterized in that CaO is added in the ground waste silver catalyst, and smelting is performed in a high-temperature electric resistance furnace to form a CaO-Al2O3 binary slag system. Silver is a good trapping agent, so that the trapping agent is not required to be added to introduce other impurities, and silver with higher purity is obtained. The method comprises the steps as follows: (1), material grinding: the waste silver catalyst is ground to 40-200 meshes; (2), material mixing: the ground waste silver catalyst powder is completely mixed with a slag forming agent CaO in a specific ratio; (3), smelting: a uniformly mixed material is placed in a graphite crucible and smelted in the high-temperature electric resistance furnace, the temperature ranges from 1,450 DEG C to 1,700 DEG C, and the time is 5-8 hours; and (4), cooling: the smelted material is naturally cooled, specific gravity of silver is larger, so that silver is deposited at the bottom of the crucible, and a slag phase and a metal phase are separated to obtain pure silver. The method disclosed by the invention can effectively shorten operation procedures and reduce production cost, and is more environment-friendly.

Description

technical field [0001] The invention relates to a method for recovering silver from silver-containing waste materials, in particular to recovering silver from waste silver catalysts for preparing ethylene oxide / ethylene glycol by oxidizing ethylene. Background technique [0002] Ethylene oxide / ethylene glycol (EO / EG) is a bulk petrochemical product second only to polyethylene among ethylene derivatives. In industry, ethylene is mainly used as raw material, and it is produced by oxidation method under the action of silver catalyst. [0003] The silver catalyst used in the petrochemical industry to prepare ethylene oxide from ethylene oxidation, containing 15-40% silver, and the carrier is α-Al 2 o 3 . When the silver catalyst loses its activity, it must be replaced, and the replacement cycle is 2 to 3 years. At present, 24 sets of EO / EG devices have been built in my country, and 13 sets are under construction. About 800-1,000 tons of waste silver catalysts need to be repla...

Claims

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Application Information

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IPC IPC(8): C22B7/00C22B11/00
CPCY02P10/20
Inventor 贺小塘赵雨韩守礼郭俊梅吴喜龙李勇王欢李子璇谭文进刘文李红梅邹蕊仙
Owner GUIYAN RESOURCE YIMEN
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