脉冲微波预处理参数对角砾岩型铀矿石破磨性能的影响

Influence of Parameters of Pulse Microwave Pre-treatment on Grindability and Crushability of Breccia Type Uranium Ore

采用自行研制功率为50kW、频率为2 450 MHz的脉冲微波装置,研究了脉冲微波功率、重复频率、占空比、辐照时间对角砾岩型铀矿石破磨性能的影响。试验结果表明:当脉冲微波功率为50kW、重复频率为500Hz、占空比为0.5、微波辐照时间为12s时,角砾岩型铀矿石的破磨性能得到了最大程度的改善,力学强度下降了43.38%,可磨性提高了41.20%。本文进一步采用美国ITASCA公司开发的PFC2D颗粒流软件,建立了脉石矿物为石英、矿石矿物为沥青铀矿的二维模型,对脉冲微波预处理提高角砾岩型铀矿石破磨性能的机制进行了模拟研究。模拟结果表明:脉冲微波预处理在角砾岩型铀矿石中衍生微裂隙是使其破磨性能得到提高的根本原因;且当脉冲微波功率为50kW、重复频率为500Hz、占空比为0.5、微波辐照时间为12s时,模型中产生的微裂隙数最多。因此,用脉冲微波预处理铀矿石时,选择与之匹配的脉冲微波预处理参数是最大限度提高其破磨性能的关键制约因素。

The effects of power density, pulse repetition frequency, duty cycle and microwave irradiation time on grindability and crushability of breccia type uranium ore are investigated by a self-developed pulsed microwave device with a mean power of 50 kW and a frequency of 2 450 MHz. The experimental results show that the grindability and crushability of the ore gained the greatest increase when the pulse repetition frequency is 500 Hz,the duty cycle is 0.5, the irradiation time is 12 s,and the mi crowave power is 50 kW. The mechanical strength is decreased by 43.38O//oo and the grindability is in- creased by 41. 200//oo. In order to reveal the mechanism involved, the particle flow code software PFC2D developed by ITASCA is employed to establish a two-dimensional model with quartz being gangue minerals and uraninite being ore mineral. PFC2D analysis shows that the microcracks is induced by the pulsed microwave pre-treatment in the ore that resulted in the grindability and crushabili ty of breccia type uranium ore; and the quantity of microcracks is reached to the most in the ore pre- treated by the pulsed microwave when the power density is 52〈 108 W/ma , the microwave irradiation time is 12 s, the pulse repetition frequency is 500 Hz, and the duty cycle is 0.5. Therefore, when pulsed microwave pretreatment is used for the processing of the ore, the key factor is to match the pa rameters of the pulsed microwave with the uranium ore to increase its grindability and crushability.