Research & Application: Steam Jet Milling in China

Processing Ultrafine Solid Waste Using Industrial Waste Heat with Low-cost

 - Mianyang, Sichuan, China

Jet Grinding is the dry method to obtaining minimum particle size effectively, but the high-energy consumption and small capacity greatly limit wide application. Creators and processors of industrial waste need to adapt large scale, low cost measures of ultrafine processing in order to make adaptation fiscally possible. Steam jet milling adopts high temperature mechanical technology and uses hot steam as media for high-speed movement to perform material pulverization.

 Currently researching the differences in medias being emitted through jet steam nozzles is Professor Chen Haiyan from Southwest University of Science and Technology, Sichuan Province, China. In his research, he compares the outlet airflow velocity with the same nozzle under different medias. The results show that compared with the 30compressed air, the crushing strength of the nozzle’s core region improved by 3 times under 300 superheated steam. Other parts of the jet steam process that were examined were the large scale and annular compound nozzles, flow field of grinding chamber, turbine classifier under superheated steam, and superheated steam bag filter.

 In a 30,000t/ year production line of desulphurization ash in a Pingshuo powder plant, ultrafine circulating fluidized bed ash was prepared by LNSJ-350A type steam jet mill.  Using superheated steam with temperature of 250and inlet pressure of 0.25 MPa supplied by a power plant, the results showed that the average particle size of the ultrafine circulating fluidized bed ash was 8.999 μm. The yield of ultrafine circulating fluidized bed ash was 73t/h. Steam consumption showed at 21.7 t and electricity consumption was 3.76k W·h per ton.

The strength and soundness conform to national standard requirements when the products are blended by a mass fraction of 10% for formulating composite Portland cement with the strength grade of 32.5.When medium particle size of desulphurization ash was about 4.76μm, the activity index could reach to 107%, which can also satisfy the requirement of S95 slag.

Professor Haiyuan, a welcomed speaker at Coal Ash Asia 2016 and 2017, explores this research alongside his colleagues at SUST, in Mianyang, Sichuan. The University was founded in 1939, and has over 29,000 students in enrolled. The campus was originally the Mianyang branch of Tsinghua University. Tsinghua University, another CAA2017 attendee, is another catalyst research facility for waste management and sustainability in China.