微波加热含碳碳酸锰矿粉升温机理

Temperature rising mechanisms of manganese carbonate fines containing coal by microwave heating

利用微波冶金炉对无烟煤和碳酸锰矿粉的混合物料进行加热,研究含碳碳酸锰矿粉在微波场中的升温机理。研究结果表明:含碳碳酸锰矿粉具有优良的微波加热特性和自还原性;在微波加热频率为2.450GHz、碳氧原子摩尔比分别为1.1,1.2和1.3时,微波加热混合物料至1473K的升温速率平均最高达到140.7K/min;不同的加热温度和配碳比下混合物料的介电常数较大,都在5.5左右,而磁导率为1左右,属介电损耗型;微波加热含碳碳酸锰矿粉的升温性能主要取决于含碳碳酸锰矿粉的电磁性能,而电磁性能的改变主要是由物料加热过程中产生的化学反应、晶体结构变化及缺陷状态的改变引起的;配碳比提高,物料吸收微波的能力有所提高;在相同的配碳比下,加热温度升高,吸收微波的能力有所减弱。

Heating experiment with the mixed materials of anthracite fines and manganese carbonate fines was done in microwave metallurgical oven. The temperature rising mechanisms of manganese carbonate fines containing coal by microwave heating were discussed. The results show that, manganese carbonate fines containing coal have good characteristics of microwave heating and self-reduction. At the molar ratios bf C atom to O atom as 1.1, 1.2 and 1.3 in the mixed materials, the averaged maximum temperature-rising rate of the mixed materials by microwave heating is 140.7 K/min at 1 473 K with the microwave frequency of 2.450 GHz. At the different containing coal ratios and heating temperatures, the value of the dielectric constant is big, 5.5, but that of the permeability is about I, so the mixed materials belong to dielectric loss. The temperature rising performance depends chiefly upon the electromagnetic performance of materials, whose change is caused primarily by the chemical reaction, the changes of crystal structural, and the changes of defects state. The bigger the containing coal ratio, the better the absorptivity of microwave. At the same containing coal ratio, the higher the heating temperature, the weaker the absorptivity of microwave.