A non-destructive cleaning process for recovering precious metals

Abstract

A process method for nondestructive cleaning and recycling of precious metal comprises an ammonia oxidation furnace, a waste heat boiler, a warm gas-gas heat exchanger, a circulating collection pump, a filter press, an intermediate tank and a washing pump which are sequentially connected in series; the washing pump can drain qualified waste water generated after cleaning to an assigned water treatment system, and the water is cyclically used after being treated; a pulse impactor is connected with an air station, the ammonia oxidation furnace and the waste heat boiler; and the pulse impactor is utilized to give out pulse air bubble blasting impacting force to perform impacting stripping on precious metal deposit attached to the surface of a coiled pipe of the waste heat boiler and oxide of the precious metal deposit. The method has no damage to equipment, and is free of pollution to the environment, a passivation agent is used for performing passivation treatment on the coiled pipe of the boiler after final cleaning, and it is guaranteed that the boiler is not corroded. Cleaning liquid can be directly drained into a waste water treatment system in an up-to-standard manner, and is cyclically used after being treated, and the method is free of pollution, achieves zero emission, has no damage to equipment and is free of pollution to the environment.

Description

Technical field: [0001] The invention relates to the field of cleaning, recycling and regeneration of precious metals produced by dilute nitric acid, in particular to a process method for non-destructive cleaning and recycling of precious metals. Background technique: [0002] The production of dilute nitric acid can be divided into normal pressure method, comprehensive method, full medium pressure method, full high pressure method, double pressurized method, etc., all of which use platinum mesh as catalyst ammonia oxidation process. After a period of use, the platinum catalytic net will lose weight and be stained. In order to ensure a high oxidation rate, it usually needs to be replaced within 180 days. According to the research of foreign companies, 30% of the lost platinum is taken away by the exhaust gas in a volatile gas state, 50% is deposited in the oxidation furnace, heat exchanger and pipeline as solid particles and oxide particles, and 20% is deposited in colloidal...

AI Technical Summary

Problems solved by technology

The tube shape of the Babcock boiler is a vertical coil, and the tube shape of the Lamont boiler is a horizontal circular coil. In order to ensure good heat exchange, the gap between the two types of boiler tubes is very small, and they overlap each other. The waste heat boiler with this structure cannot be cleaned mechanically, and there is a safety risk in pickling

[0003] The existing mechanical scraping and grinding recovery process and high-pressure water jet mechanical cleaning and recovery process can only clean straight pipe equipment, which will damage the equipment and shorten the service life of the equipment. The service life, the difficulty of waste liquid treatment, the non-destructive cleaning and recovery of precious metals, solve the problems that the double pressurized dilute nitric acid device coil boiler machinery cannot be cleaned, pickling and corrosion equipment, and the waste liquid treatment is difficult.

Images