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Rough Purification Process Of Diamond Micropowder

June 03,2023

Generally, the raw materials of diamond micro powder are mostly low-grade RVD diamond or diamond micro powder synthesized by explosion, and the raw materials themselves contain a small amount of impurities such as graphite, catalyst metal and pyrophyllite. At the same time, a large amount of metal impurities will also be introduced during the later crushing and shaping processes. High impurity content will reduce the overall hardness of diamond and affect the performance of deep processing tools. In order to meet the requirements for product purity in subsequent grading processes, these impurities must be removed before entering the grading process.

At present, chemical impurity removal and electrolytic purification techniques are commonly used for the purification of artificial diamond micropowders. The latter is mainly used when there are many alloy catalysts in diamond materials, in order to achieve the goal of recycling catalyst metals. However, in practical work, due to the slow dissolution of alloy catalysts and low production efficiency, it is difficult to adapt to the requirements of production development. In contrast, according to the different chemical characteristics of the impurities in the diamond, the chemical method uses different chemical reagents to treat the impurities separately, which can obtain better purification effect, that is, the “three removal” process commonly used in industry: acid removal of alloy catalyst, strong oxidant removal of graphite, alkali melting of pyrophyllite and other three stages of work. According to the characteristics of good chemical stability of diamond and no reaction with acid and strong oxidant at high temperature, chemical methods are generally used to purify diamond. The main impurities in diamonds that complete the crushing and shaping processes are metals, which can undergo oxidation-reduction reactions with acids to generate soluble salts. By utilizing this feature and treating them with appropriate acids, the vast majority of metal impurities can be removed, as well as impurities such as graphite.

The general operation method for acid treatment is to weigh a certain amount of diamond powder, place it in a 5000ml glass beaker or other acid and high temperature resistant container, add an appropriate amount of acid solution, and place the beaker on an electric heating plate or industrial electric furnace in a fume hood for heating. As the temperature increases, the reaction gradually intensifies. After the reaction completely stops, stop heating and remove the container from the heat source. After the material cools to room temperature, Pour out the upper layer of waste acid, wash with water until neutral, and transfer to the grading process.

In industrial production, due to the need for refined purification treatment after the later stage of classification, the crude purification process should minimize costs while meeting the requirements of the classification process. Generally, the chemical reagents used are mostly industrial pure.

Due to the low content of pyrophyllite and graphite in diamond raw materials. In order to simplify the processing process, the general rough purification process no longer requires specialized treatment. For products with special requirements, the finished product is specifically subjected to post-processing after grading. In the production process of diamond powder, various chemical reagents are used in the purification process, and a large amount of harmful gases and wastewater are discharged during the treatment process, which poses a threat to the occupational health of operators and pollutes the environment. In order to improve the working environment of operators and reduce exhaust and wastewater emissions. Some diamond powder production enterprises have begun to try to change their original purification methods, replacing the original open beaker heating treatment process with the use of large enclosed reaction kettles for treatment. The reaction kettle adopts electric heating or indirect heating with thermal oil, and the material is quartz glass or lined with enamel steel material. According to the production scale, reaction kettles of various specifications such as 20 liters, 50 liters, and 100 liters can be selected. The equipment is equipped with automatic stirring, automatic temperature control, waste gas neutralization and absorption, and acid vapor condensation reflux devices. Using a reaction kettle for purification treatment not only increases the single processing capacity and reduces personnel labor intensity, but also has significant effects in saving energy, improving labor conditions, and protecting the environment.

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