METHOD OF CLEANING LARGE CRYSTALS OF NATURAL DIAMONDS Russian patent published in 2012 - IPC C30B33/04 C30B33/12 C30B29/04 C01B31/06 

FIELD: chemistry.

SUBSTANCE: method involves step-by-step treatment of diamonds in an autoclave at high temperature and pressure, including a step for cleaning with a mixture of nitric acid and hydrogen peroxide and a step for cleaning with a mixture of concentrated nitric, hydrochloric and hydrofluoric acids under the effect of microwave radiation. After the step for cleaning with nitric acid and hydrogen peroxide, the diamonds are treated under the effect of microwave radiation with hydrochloric acid in gaseous phase at temperature 215-280°C for 15-300 minutes. Further, the diamonds are treated with distilled water at temperature 160-280°C for 5-30 minutes in an autoclave in liquid phase. At the step for cleaning with a mixture of nitric acid and hydrogen peroxide, treatment is carried out with the following volume ratio of components: nitric acid and hydrogen peroxide 4-10:1-3, respectively, at temperature 215-280°C for 15-540 minutes in liquid phase in a system with external heating or in a gaseous phase under the effect of microwave radiation. At the step for cleaning with a mixture of concentrated nitric, hydrochloric and hydrofluoric acids, treatment under the effect of microwave radiation is carried out with the following volume ratio of components: nitric, hydrochloric and hydrofluoric acid 1-6:1-6:1-3, respectively, in gaseous phase at temperature 215-280°C for 15-300 minutes.

EFFECT: invention increases the effectiveness of the process of cleaning diamonds larger than 4,0 mm with high efficiency of the equipment used.

3 cl, 3 dwg, 2 tbl, 1 ex